Experiment https://scienceblogs.com/ en "CERN Invented the Web" Isn't an Argument for Anything https://scienceblogs.com/principles/2017/03/24/cern-invented-the-web-isnt-an-argument-for-anything <span>&quot;CERN Invented the Web&quot; Isn&#039;t an Argument for Anything</span> <div class="field field--name-body field--type-text-with-summary field--label-hidden field--item"><p>I mentioned in passing in the <a href="https://www.forbes.com/sites/chadorzel/2017/03/23/the-most-important-science-to-fund-is-the-hardest-to-explain/#23a5f5b72717">Forbes post about science funding</a> that I'm thoroughly sick of hearing about how the World Wide Web was invented at CERN. I got into an argument about this a while back on Twitter, too, but had to go do something else and couldn't go into much detail. It's probably worth explaining at greater-than-Twitter length, though, and a little too inside-baseball for Forbes, so I'll write something about it here.</p> <p>At its core, the "CERN invented WWW" argument is a "Basic research pays off in unexpected ways" argument, and in that sense, it's fine. The problem is, it's not anything more than that-- its fine as an argument for funding basic research as a general matter, but it's not an argument <em>for</em> anything in particular.</p> <p>What bugs me is now when it's used as a general "Basic research is good" argument, but that it's used as a catch-all argument for giving particle physicists whatever they want for whatever they decide they want to do next. It's used to steamroll past a number of other, perfectly valid, arguments about funding priorities within the general area of basic physics research, and that gets really tiresome.</p> <p>Inventing WWW is great, but it's not an argument for particle physics in particular, precisely because it was a weird spin-off that nobody expected, or knew what to do with. In fact, you can argue that much of the impact of the Web was enabled precisely because CERN didn't really understand it, and Time Berners-Lee just went and did it, and gave the whole thing away. You can easily imagine a different arrangement where Web-like network technologies were developed by people who better understood the implications, and operated in a more proprietary way from the start.</p> <p>As an argument for funding particle physics in particular, though, the argument undermines itself precisely due to the chance nature of the discovery. Past performance does not guarantee future results, and the fact that CERN stumbled into a transformative discovery once doesn't mean you can expect anything remotely similar to happen again.</p> <p>The success of the Web is all too often invoked as a way around a very different funding argument, though, where it doesn't really apply, which is an argument about the relative importance of Big Science. That is, a side spin-off like the Web is a great argument for funding basic science in general, but it doesn't say anything about the relative merits of spending a billion dollars on building a next-generation particle collider, as opposed to funding a thousand million-dollar grants for smaller projects in less abstract areas of physics.</p> <p>There are arguments that go both ways on that, and none of them have anything to do with the Web. On the Big Science side, you can argue that working at an extremely large scale necessarily involves pushing the limits of engineering and networking and working in those big limits might offer greater opportunities for discovery. On the small-science side, you can argue that a greater diversity of projects and researchers offers more chances for the unexpected to happen compared to the same investment in a single enormous project. </p> <p>I'm not sure what the right answer to that question is-- given my background, I'm naturally inclined toward the "lots of small projects (in subfields like the one I work in)" model, but I can see some merit to the arguments about working at scale. I think it <em>is</em> a legitimate question, though, one that needs to be considered seriously, and not one that can be headed off by using WWW as a Get Funding Forever trump card for particle physics.</p> </div> <span><a title="View user profile." href="/author/drorzel" lang="" about="/author/drorzel" typeof="schema:Person" property="schema:name" datatype="">drorzel</a></span> <span>Fri, 03/24/2017 - 05:58</span> <div class="field field--name-field-blog-tags field--type-entity-reference field--label-inline"> <div class="field--label">Tags</div> <div class="field--items"> <div class="field--item"><a href="/tag/academia" hreflang="en">Academia</a></div> <div class="field--item"><a href="/tag/experiment" hreflang="en">Experiment</a></div> <div class="field--item"><a href="/tag/funding" hreflang="en">Funding</a></div> <div class="field--item"><a href="/tag/physics" hreflang="en">Physics</a></div> <div class="field--item"><a href="/tag/policy" hreflang="en">Policy</a></div> <div class="field--item"><a href="/tag/science" hreflang="en">Science</a></div> </div> </div> <section> <article data-comment-user-id="0" id="comment-1649401" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1490352102"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>What Tim Berners-Lee did was invent HTTP, which went on to become the standard for what we call the World Wide Web. But there were competing protocols in the early 1990s: gopher and archie, and even FTP (an even older protocol which is still used today in specific situations). It was hardly inevitable that HTTP would become the standard.</p> <p>The main thing about HTTP was that it was intended to be independent of client hardware and software. Some scientists in those days used VAX machines, and others used Unix boxes. Some even used MS-DOS (early versions of Windows were only recently available at the time and did not achieve significant market penetration until a few years later). HTTP didn't care what you had on your end, as long as you could connect to the server. Which made it a good solution for a problem experimental particle physicists had at the time: how to share their data with their collaborators.</p> <p>So yes, "CERN invented the Web" is a valid argument for funding science in general, but it is not a valid argument for being more specific about what science is to be funded.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649401&amp;1=default&amp;2=en&amp;3=" token="PcQgxGME7irzEP1eyRdbuq4vgI4VAboOsbvUYXQI9RA"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Eric Lund (not verified)</span> on 24 Mar 2017 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649401">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649402" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1490354544"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>Wasn't the Internet itself a US Government-funded DARPA project? CERN only created the WWW as an easy way to connect and navigate it.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649402&amp;1=default&amp;2=en&amp;3=" token="9eyOSc8haOr_9ZRvtE4obh6UZIUsXpmL-18ROqnI7xo"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">KAL (not verified)</span> on 24 Mar 2017 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649402">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649403" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1490357981"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>We could equally argue that GPS is a reason to fund differential geometry (no differential geometry =&gt; no general relativity =&gt; GPS doesn't work) and algebraic geometry (no algebraic geometry =&gt; no arithmetic of elliptic curves =&gt; what do you think internet security protocols are based on?). In general, I'd say what it means is fund *all* basic research, because you don't know which part of it will be applicable (and when).</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649403&amp;1=default&amp;2=en&amp;3=" token="YHR9P8T-ATJiG5dYDjmL-EIU9Dfu3AWb1ZDKaZG0TnM"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Barbara (not verified)</span> on 24 Mar 2017 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649403">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649404" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1490603592"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>Chad, your post is disappointing. It's a straw-man and it's parochial and leaves an inaccurate impression about my field. While I cannot speak for every single one of my particle physics (and yes, I work at CERN) colleagues, as a former chair of my department, former chair of the DPF, former chair of the Fermilab Users Executive Committee, former co-convener of the Energy Frontier working group for the (sort of decadal) "snowmass study" about the future physics in particle physics, and former chair of the US ATLAS Institutional board I have many times been called on to justify basic research in general and particle physics in particular.</p> <p>I've never used the WWW as a reason to fund particle physics in the spirit that you suggest and certainly never seen anyone do so. "Steamroll" is just not fair, nor is the implication that particle physics gets what it wants because it "invented" the WWW. Of course it didn't. The infrastructure was in place in the US exactly as KAL notes, as a DARPA project and a matter of national preparedness in the cold war. And, as Eric points out, HTTP was Berners-Lee's contribution. That wasn't entirely trivial and it did break conceptual ground about how the large group communications problems that LEP experiments were facing might be facilitated.</p> <p>We have often pointed at the WWW as an example of how problems get solved in science...maybe even problems that weren't necessarily recognized as problems at all. But we always do so in the broader context of increased funding for all of basic research. In fact, the GPS example from Barbara is perfect. Who would have thought that GR would be a practical need? </p> <p>The best spinoff argument for particle physics (It's somewhat controversial as to whether "spinoff" should ever be used as an argument. I think it's fair.) is accelerator physics which enjoys the position of having two feet planted firmly in both the basic research landscape as well as an increasingly vibrant applied landscape. We don't do accelerator-based research anywhere in the world without them.</p> <p>Particle physics doesn't get everything it wants. I don't know a single research group in the US that has not seen significant cuts in university research grants over at least the last 3 cycles. So again, you leave an inaccurate implication. </p> <p>The "we'll do better with your money than you will" argument (again "steamroll" sticks in my craw) is not a winner for anyone. We've always argued on behalf of my physics - and yours - and everyone's basic research, especially at universities and I wish you'd do the same. I'm glad this wasn't in Forbes, frankly...which was a good article, apart from the short swipe at particle physics.</p> <p>I enjoy your books, but this post, as I say, disappointed me a lot.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649404&amp;1=default&amp;2=en&amp;3=" token="9iaQGyRP4_y1eDdy11ftEzvyRL_xg4UAcVZ5MFqBkqs"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Chip Brock (not verified)</span> on 27 Mar 2017 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649404">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="50" id="comment-1649405" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1490706679"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>I'm sorry to disappoint (but then, I'll be happy to refund you the full cost of the post...), and glad to hear you don't use that argument in that way. If you've never heard it used as such, though, we're clearly not talking to the same set of people. </p> <p>I've heard the WWW invoked innumerable times when the question of whether particle physics is a good investment relative to other areas of science. I've even had someone say to me "Return on investment? What, the Web isn't good enough for you?" (or words very close to those).</p> <p>I agree that there's a good case to be made, particularly in the area of accelerator physics, that development of a next generation machine might offer good opportunities for technological advancements that will have impact well outside the fundamental physics community. I'd like to see that argument made more frequently, particularly in public outreach contexts. It's far more common, in my experience, for discussion of particle-physics spinoffs to begin and end with the Web, though, and I think that's a shame.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649405&amp;1=default&amp;2=en&amp;3=" token="JZuy2_azs1GCKlFwgswnrUlHYG0--QCZwMreAPH7WQA"></drupal-render-placeholder> </div> <footer> <em>By <a title="View user profile." href="/author/drorzel" lang="" about="/author/drorzel" typeof="schema:Person" property="schema:name" datatype="">drorzel</a> on 28 Mar 2017 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649405">#permalink</a></em> <article typeof="schema:Person" about="/author/drorzel"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/author/drorzel" hreflang="en"><img src="/files/styles/thumbnail/public/pictures/after1-120x120.jpg?itok=XDhUCPqP" width="100" height="100" alt="Profile picture for user drorzel" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649406" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1491087041"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>I find the accelerator argument to be totally bogus, because accelerators and accelerator-based treatments came out of nuclear physics back when the highest energy physics used cosmic rays to do experiments in balloons or on mountain tops rather than accelerators in a laboratory. </p> <p>Eric, @ #1,misses the important detail that ftp offered most of what you need to share data. It wasn't neat and tidy if you didn't have a decent sense of how to put together directory tree, but it enabled the easy movement of data and was widely used for that purpose. It didn't have to be replaced if the users were all techno-geeks. </p> <p>You all seem to miss the importance of Hypercard (a vast improvement over a directory tree and Readme files) to the idea of hypertext. That came out of Apple, not government research, but it was signficant that Apple machines were widely used on the non-computing side of physics research. HTTP was a very clever invention of a way to make the Hypercard idea work independently of hardware and o/s platforms. Maybe it wasn't inevitable, but I know people who argued ad nauseum that people with messy file systems to manage should use it, only to be met with "but I use a VAX", and never went further than to mutter under their breath. .</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649406&amp;1=default&amp;2=en&amp;3=" token="bUhSQNaSkUvRJrY2K03sWVhg94AUXiDhRcNpLZI3PzA"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">CCPhysicist (not verified)</span> on 01 Apr 2017 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649406">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> </section> <ul class="links inline list-inline"><li class="comment-forbidden"><a href="/user/login?destination=/principles/2017/03/24/cern-invented-the-web-isnt-an-argument-for-anything%23comment-form">Log in</a> to post comments</li></ul> Fri, 24 Mar 2017 09:58:57 +0000 drorzel 49111 at https://scienceblogs.com Physics Blogging Round-Up: December https://scienceblogs.com/principles/2017/01/13/physics-blogging-round-up-december <span>Physics Blogging Round-Up: December</span> <div class="field field--name-body field--type-text-with-summary field--label-hidden field--item"><p>This one's late because I acquired a second class for the Winter term on very short notice. I was scheduled to teach our sophomore-level "Modern Physics" class, plus the lab, but a colleague who was scheduled to teach relativity for non-majors had a medical issue, and I'm the only other one on staff who's ever taught it, so now I'm doing two courses instead of one. Whee!</p> <p>Anyway, here are my December posts from Forbes:</p> <p>-- <a href="http://www.forbes.com/sites/chadorzel/2016/12/02/science-is-not-that-special/#2373872175f5">Science Is Not THAT Special</a>: Another in a long series of posts grumbling about the way we set science off from other pursuits and act as if the problems facing it are unique. In reality, a lot of what we talk about as issues of science education are challenges faced by pretty much every other profession as well, with less hand-wringing.</p> <p>-- <a href="http://www.forbes.com/sites/chadorzel/2016/12/09/the-surprisingly-complicated-physics-of-sliding-on-ice/">The Surprisingly Complicated Physics of Sliding On Ice</a>: Revisiting that time a couple of years ago when I wrote a bunch about the physics of luge, this time talking about a much more basic question: Why is ice slippery?</p> <p>-- <a href="http://www.forbes.com/sites/chadorzel/2016/12/12/white-rabbit-project-physics-g-forces/">"White Rabbit Project" Physics: G-Forces</a>: I had a bunch of conversations with the producers of the new Netflix show "White Rabbit Project" a year or so ago, and some of what we talked about turned into an episode on "g-forces" in acceleration.</p> <p>-- <a href="http://www.forbes.com/sites/chadorzel/2016/12/19/alpha-experiment-shines-new-light-on-antimatter/">ALPHA Experiment Shines New Light On Antimatter</a>: The ALPHA collaboration at CERN has done the first spectroscopy of antihydrogen. It's pretty rudimentary by the standards of precision measurement folks, but still an important step.</p> <p>-- <a href="http://www.forbes.com/sites/chadorzel/2016/12/29/what-should-you-expect-from-low-energy-physics-in-2017-its-hard-to-say/">What Should You Expect From Low-Energy Physics In 2017? It's Hard To Say</a>: I was reading posts about (high-energy) physics news to look for in 2017, and realized I couldn't write an AMO physics equivalent. So I wrote about <em>why</em> I couldn't make predictions about my home field.</p> <p>So there, two weeks into January, is what I wrote about in December. I've got a couple of posts up already this month, but we'll save them for the January recap, which I'll try to get posted before March. No promises, though, because this extra class has thrown things into disarray...</p> </div> <span><a title="View user profile." href="/author/drorzel" lang="" about="/author/drorzel" typeof="schema:Person" property="schema:name" datatype="">drorzel</a></span> <span>Fri, 01/13/2017 - 00:20</span> <div class="field field--name-field-blog-tags field--type-entity-reference field--label-inline"> <div class="field--label">Tags</div> <div class="field--items"> <div class="field--item"><a href="/tag/atoms-and-molecules" hreflang="en">Atoms and Molecules</a></div> <div class="field--item"><a href="/tag/blogs" hreflang="en">Blogs</a></div> <div class="field--item"><a href="/tag/experiment" hreflang="en">Experiment</a></div> <div class="field--item"><a href="/tag/forbes-recap" hreflang="en">Forbes Recap</a></div> <div class="field--item"><a href="/tag/physics" hreflang="en">Physics</a></div> <div class="field--item"><a href="/tag/science" hreflang="en">Science</a></div> </div> </div> <section> </section> <ul class="links inline list-inline"><li class="comment-forbidden"><a href="/user/login?destination=/principles/2017/01/13/physics-blogging-round-up-december%23comment-form">Log in</a> to post comments</li></ul> Fri, 13 Jan 2017 05:20:09 +0000 drorzel 49106 at https://scienceblogs.com Physics Blogging Round-Up: ARPES, Optics, Band Gaps, Radiation Pressure, Home Science, and Catastrophe https://scienceblogs.com/principles/2016/04/19/physics-blogging-round-up-arpes-optics-band-gaps-radiation-pressure-home-science-and-catastrophe <span>Physics Blogging Round-Up: ARPES, Optics, Band Gaps, Radiation Pressure, Home Science, and Catastrophe</span> <div class="field field--name-body field--type-text-with-summary field--label-hidden field--item"><p>It's been a while since I last rounded up physics posts from Forbes, so there's a good bunch of stuff on this list:</p> <p>-- <a href="http://www.forbes.com/sites/chadorzel/2016/03/22/how-do-physicists-know-what-electrons-are-doing-inside-matter/">How Do Physicists Know What Electrons Are Doing Inside Matter?</a>: An explanation of Angle-Resolved Photo-Electron Spectroscopy (ARPES), one of the major experimental techniques in condensed matter. I'm trying to figure out a way to list "got 1,800 people to read a blog post about ARPES" as one of my professional accomplishments on my CV.</p> <p>-- <a href="http://www.forbes.com/sites/chadorzel/2016/03/25/the-optics-of-supermans-x-ray-vision/">The Optics Of Superman's X-Ray Vision</a>: Spinning off a post of Rhett's, a look at why humanoid eyes just aren't set up to work with x-rays.</p> <p>-- <a href="http://www.forbes.com/sites/chadorzel/2016/03/30/why-do-solids-have-band-gaps/">Why Do Solids Have Band Gaps?</a>: A conceptual way to see why there are some energies that electrons simply can not have inside a periodic structure.</p> <p>-- <a href="http://www.forbes.com/sites/chadorzel/2016/03/31/how-tropical-birds-use-quantum-physics/">How Tropical Birds Use Quantum Physics</a>: Blue feathers on many birds aren't blue because of pigment, but thanks to the same physics that gives solids band gaps.</p> <p>-- <a href="http://www.forbes.com/sites/chadorzel/2016/04/08/why-do-we-teach-old-physics-because-it-works/">Why Do We Teach Old Physics? Because It Works</a>: We had another round of people lamenting the emphasis on "old" topics in introductory courses; here's my defense of the standard curricular order.</p> <p>-- <a href="http://www.forbes.com/sites/chadorzel/2016/04/12/how-hard-does-the-sun-push-on-the-earth/">How Hard Does The Sun Push On the Earth?</a> In which one of The Pip's silly superhero books gets me thinking about radiation pressure forces.</p> <p>-- <a href="http://www.forbes.com/sites/chadorzel/2016/04/13/how-to-use-a-laser-pointer-to-measure-tiny-things/">How To Use A Laser Pointer To Measure Tiny Things</a>: In which I use a green laser to settle the question of who in Chateau Steelypips has the thickest hair.</p> <p>-- <a href="http://www.forbes.com/sites/chadorzel/2016/04/15/dont-just-talk-about-science-with-your-kids-do-science-with-your-kids/">Don't Just Talk About Science With Your Kids, DO Science With Your Kids</a>: A simple home experiment, and a pitch for the importance of doing simple experiments at home.</p> <p>-- <a href="http://www.forbes.com/sites/chadorzel/2016/04/18/how-quantum-physics-starts-with-your-toaster/">How Quantum Physics Starts With Your Toaster</a>: A blog version of my half-hour fake class on the "ultraviolet catastrophe" and why Planck needed the quantum hypothesis to solve black-body radiation.</p> <p>Both blogs are likely to be on a sort of hiatus for the next little bit. I'm giving a talk at Mount Holyoke tonight, which will get me home really late, then Thursday and Friday I'm going to NYC for a <a href="http://spaceappsnyc.com/">space conference</a>. Then on Saturday, we're flying to Florida with the kids and my parents, and going on a Disney cruise in the Caribbean for all of next week. Which will provide a badly needed opportunity to kick back by the pool, because oh, God, so busy...</p> </div> <span><a title="View user profile." href="/author/drorzel" lang="" about="/author/drorzel" typeof="schema:Person" property="schema:name" datatype="">drorzel</a></span> <span>Tue, 04/19/2016 - 02:15</span> <div class="field field--name-field-blog-tags field--type-entity-reference field--label-inline"> <div class="field--label">Tags</div> <div class="field--items"> <div class="field--item"><a href="/tag/blogs" hreflang="en">Blogs</a></div> <div class="field--item"><a href="/tag/condensed-matter" hreflang="en">Condensed Matter</a></div> <div class="field--item"><a href="/tag/education" hreflang="en">education</a></div> <div class="field--item"><a href="/tag/experiment" hreflang="en">Experiment</a></div> <div class="field--item"><a href="/tag/forbes-recap" hreflang="en">Forbes Recap</a></div> <div class="field--item"><a href="/tag/media-0" hreflang="en">In the Media</a></div> <div class="field--item"><a href="/tag/optics" hreflang="en">Optics</a></div> <div class="field--item"><a href="/tag/outreach" hreflang="en">Outreach</a></div> <div class="field--item"><a href="/tag/personal" hreflang="en">personal</a></div> <div class="field--item"><a href="/tag/physics" hreflang="en">Physics</a></div> <div class="field--item"><a href="/tag/quantum-optics" hreflang="en">Quantum Optics</a></div> <div class="field--item"><a href="/tag/science" hreflang="en">Science</a></div> </div> </div> <section> </section> <ul class="links inline list-inline"><li class="comment-forbidden"><a href="/user/login?destination=/principles/2016/04/19/physics-blogging-round-up-arpes-optics-band-gaps-radiation-pressure-home-science-and-catastrophe%23comment-form">Log in</a> to post comments</li></ul> Tue, 19 Apr 2016 06:15:51 +0000 drorzel 49060 at https://scienceblogs.com Attempted Mpemba Effect https://scienceblogs.com/principles/2016/02/16/attempted-mpemba-effect <span>Attempted Mpemba Effect</span> <div class="field field--name-body field--type-text-with-summary field--label-hidden field--item"><p>One of my favorite modern tales of scientific discovery is <a href="http://scienceblogs.com/principles/2014/12/21/advent-calendar-of-science-stories-21-hot-and-cold/">the Mpemba Effect</a>, named after Erasto Mpemba, a schoolboy in Tanzania who noticed while making ice cream that hot mix put in the freezer solidified faster than cold. This counter-intuitive result has been replicated a bunch of times, and physicists and chemists continue to debate the reason for it.</p> <p>It was bitterly cold this weekend, dipping down into the negative Fahrenheit, which wasn't great for, you know, leaving the house, but did provide an opportunity to test the Mpemba Effect. Because when the icy winds of winter blow, that's a great time to do SCIENCE!...</p> <div style="width: 610px;display:block;margin:0 auto;"><a href="/files/principles/files/2016/02/mpemba_materials.jpg" rel="attachment wp-att-10572"><img src="/files/principles/files/2016/02/mpemba_materials.jpg" alt="Materials for an attempt to observe the Mpemba Effect." width="600" height="400" class="size-full wp-image-10572" /></a> Materials for an attempt to observe the Mpemba Effect. </div> <p>One of the tricky things about the Mpemba Effect is quantifying what it means for hot liquid to freeze faster than cold, but I thought of a way to (attempt to) handle that, which was another reason for running the test. So I grabbed a couple of water glasses out of the cabinet, and filled one with 200g of filtered tap water at 18C, and the other with filtered tap water heated in the microwave, at 81C. The water glasses had a mass of about 350g; there's a +/-5g error on all those masses, because the cheap kitchen scale we have at home only reads to the nearest 5g.</p> <p>Then, I took the two glasses and put them out on the patio table:</p> <div style="width: 610px;display:block;margin:0 auto;"><a href="http://scienceblogs.com/principles/files/2016/02/mpemba_start.jpg" rel="attachment wp-att-10569"><img src="http://scienceblogs.com/principles/files/2016/02/mpemba_start.jpg" alt="Starting condition for a science experiment." width="600" height="400" class="size-full wp-image-10569" /></a> Starting condition for a science experiment. </div> <p>(Actually, I put them like this for the photo, then separated them a little more, just to make sure that there wasn't any thermal contact between the samples...)</p> <p>I left them outside for about two hours, which was long enough for them to partially freeze, but not completely:</p> <div style="width: 610px;display:block;margin:0 auto;"><a href="/files/principles/files/2016/02/mpemba_after.jpg" rel="attachment wp-att-10571"><img src="/files/principles/files/2016/02/mpemba_after.jpg" alt="Frozen water from the Mpemba Effect experiment." width="600" height="400" class="size-full wp-image-10571" /></a> Frozen water from the Mpemba Effect experiment. </div> <p>I weighed the two glasses again, and found that the hot water had lost some mass-- the total mass was about 540g, so 10g down from the start. This was presumably due to evaporation-- you can just see a cloud of steam rising from it in the outdoor photo. The cold water didn't lose any mass, continuing to register at 550g, though again: cheap kitchen scale.</p> <p>To get at the amount of freezing, I took a steak knife and chopped a hole in the top layer of ice in each glass, then poured out the liquid water from underneath. Then I weighed the glasses again: the cold water glass plus solid ice clocked in at 455g, and the hot water glass with ice at 420g.</p> <p>To put that in terms of a freezing fraction, the cold water had 105g of ice out of 200 g of water, or 53% ice, and the hot water had 70g of ice in 190g of water, so 37% ice. </p> <p>So, as an attempt to observe the Mpemba Effect, this was pretty much a complete failure. Alas. This isn't entirely surprising, though, as the effect is notoriously finnicky. Which is why it's been argued about in the literature for 40-odd years. I thought about repeating the trial with slightly different conditions-- one of the things you see in a lot of the discussions of this is a comparison between water that was heated and allowed to cool before being put in the freezer and water that was put in the freezer while hot. The idea being that heating may drive off some impurities, changing the water a bit. I didn't try that on Sunday because I was in a hurry to set it up before dinner and the kids' bedtime, and we got snow on Monday that would've messed up the conditions. But it's something I'll keep in mind for the next time it's unpleasantly cold...</p> </div> <span><a title="View user profile." href="/author/drorzel" lang="" about="/author/drorzel" typeof="schema:Person" property="schema:name" datatype="">drorzel</a></span> <span>Tue, 02/16/2016 - 03:43</span> <div class="field field--name-field-blog-tags field--type-entity-reference field--label-inline"> <div class="field--label">Tags</div> <div class="field--items"> <div class="field--item"><a href="/tag/everyday" hreflang="en">Everyday</a></div> <div class="field--item"><a href="/tag/experiment" hreflang="en">Experiment</a></div> <div class="field--item"><a href="/tag/history-science" hreflang="en">History of Science</a></div> <div class="field--item"><a href="/tag/physics" hreflang="en">Physics</a></div> <div class="field--item"><a href="/tag/science" hreflang="en">Science</a></div> <div class="field--item"><a href="/tag/thermostatmech" hreflang="en">Thermo/StatMech</a></div> </div> </div> <section> <article data-comment-user-id="0" id="comment-1649125" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1455614441"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>If the effect is real, it is likely subtle. It might manifest for a smaller temperature difference.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649125&amp;1=default&amp;2=en&amp;3=" token="v4pJlqk5Pt3oV97o6S--8zHWT09VL9HoXcHLj21sO-I"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">David Vogel (not verified)</span> on 16 Feb 2016 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649125">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="50" id="comment-1649126" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1455614590"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>It's definitely a real effect, as there's a moderately substantial body of literature documenting it stretching back to the late 1960's. I didn't check the temperature difference in typical experiments, though, because this was slapped together quickly.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649126&amp;1=default&amp;2=en&amp;3=" token="x9lV_5qHBjhQDpvct_ZPtVPz_OnpWNdZNF-AZnDxEfM"></drupal-render-placeholder> </div> <footer> <em>By <a title="View user profile." href="/author/drorzel" lang="" about="/author/drorzel" typeof="schema:Person" property="schema:name" datatype="">drorzel</a> on 16 Feb 2016 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649126">#permalink</a></em> <article typeof="schema:Person" about="/author/drorzel"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/author/drorzel" hreflang="en"><img src="/files/styles/thumbnail/public/pictures/after1-120x120.jpg?itok=XDhUCPqP" width="100" height="100" alt="Profile picture for user drorzel" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649127" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1455618256"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>My students did a research project on it and saw the effect with ice cream. We used stand alone ice cream makers adapted to fit a thermocouple so we could measure the rate of change in temp. There was a small but distinct increase in the rate of cooling for the hot ice cream mix.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649127&amp;1=default&amp;2=en&amp;3=" token="DWweXfOwngeODijS_63oKggwp0fhJqCJ1SEG4HE73bI"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">labcat (not verified)</span> on 16 Feb 2016 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649127">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649128" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1455620044"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>labcat, the *rate* of cooling (that is, change in temperature per time) should definitely be larger for the hotter sample - that's well understood. Cooling rate is a function of temperature difference, so 80 degree water in a 10 degree environment will have a larger cooling rate than 50 degree water in a 10 degree environment.</p> <p>Unless you're saying that the initially hot water has a larger cooling rate when it is 50 degrees than water which started out at 50 degrees did when it was 50 degrees. That would be an interesting effect (and necessary for the Mpemba effect).</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649128&amp;1=default&amp;2=en&amp;3=" token="BXr-YjZppJ0JBinyda0ozh8BEY8h2Hcnm7WgeSg2Rq4"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Tom (not verified)</span> on 16 Feb 2016 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649128">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649129" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1455637630"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>Has any of the formal (or for that matter informal) literature successfully replicating the phenomenon used plain water? I wonder if the fact that ice cream mix is a lipid-rich suspension is not somehow necessary.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649129&amp;1=default&amp;2=en&amp;3=" token="BRa4BTLL0kpGPKR26M2IEOpRhWFYKKaaPfO9grc3M9w"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">jane (not verified)</span> on 16 Feb 2016 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649129">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649130" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1456401927"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>I would suggest repeating the experiment, although next time, leave two empty glasses outside where you intend to run the experiment, and pour the water from the first two glasses into the pre-chilled ones. My hypothesis being, warming the glass in the microwave likely stored some heat energy in the glass surrounding the water. In the Mpemba setup, it's the water alone which freezes at a faster rate, not water continually heated by an external source. The constant re-application of heat into the water would not be consistent with the parameters of the original experiment.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649130&amp;1=default&amp;2=en&amp;3=" token="h_9R677uhLBMb8EVnycDLFG55b3eA4Dwh07iMutrTVc"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">ENT-TT (not verified)</span> on 25 Feb 2016 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649130">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> </section> <ul class="links inline list-inline"><li class="comment-forbidden"><a href="/user/login?destination=/principles/2016/02/16/attempted-mpemba-effect%23comment-form">Log in</a> to post comments</li></ul> Tue, 16 Feb 2016 08:43:07 +0000 drorzel 49030 at https://scienceblogs.com 165/366: Wintry Science https://scienceblogs.com/principles/2016/02/15/165366-wintry-science <span>165/366: Wintry Science</span> <div class="field field--name-body field--type-text-with-summary field--label-hidden field--item"><p>It was bitterly cold over the weekend here in the Northeast, with daytime high temepratures in the single digits Fahrenheit. This has little to recommend it in terms of, you know, leaving the house, but it did provide an opportunity to try some SCIENCE!</p> <p>Unfortunately, I left the notepad with the data (such as it is) on it at home when I came to Starbucks to write, so I can't do the detailed write-up. I'll use it for the photo of the day, though, from which you can probably guess what I was trying to do:</p> <div style="width: 610px;display:block;margin:0 auto;"><a href="/files/principles/files/2016/02/mpemba_start.jpg" rel="attachment wp-att-10569"><img src="/files/principles/files/2016/02/mpemba_start.jpg" alt="Starting condition for a science experiment." width="600" height="400" class="size-full wp-image-10569" /></a> Starting condition for a science experiment. </div> <p>Detailed explanation of methods and results later today, or maybe tomorrow.</p> </div> <span><a title="View user profile." href="/author/drorzel" lang="" about="/author/drorzel" typeof="schema:Person" property="schema:name" datatype="">drorzel</a></span> <span>Mon, 02/15/2016 - 02:39</span> <div class="field field--name-field-blog-tags field--type-entity-reference field--label-inline"> <div class="field--label">Tags</div> <div class="field--items"> <div class="field--item"><a href="/tag/366" hreflang="en">366</a></div> <div class="field--item"><a href="/tag/everyday" hreflang="en">Everyday</a></div> <div class="field--item"><a href="/tag/experiment" hreflang="en">Experiment</a></div> <div class="field--item"><a href="/tag/physics" hreflang="en">Physics</a></div> <div class="field--item"><a href="/tag/pictures" hreflang="en">Pictures</a></div> </div> </div> <section> </section> <ul class="links inline list-inline"><li class="comment-forbidden"><a href="/user/login?destination=/principles/2016/02/15/165366-wintry-science%23comment-form">Log in</a> to post comments</li></ul> Mon, 15 Feb 2016 07:39:09 +0000 drorzel 49029 at https://scienceblogs.com Fluid Dynamics Is Weird: Bathroom Sink Edition https://scienceblogs.com/principles/2016/01/25/fluid-dynamics-is-weird-bathroom-sink-edition <span>Fluid Dynamics Is Weird: Bathroom Sink Edition</span> <div class="field field--name-body field--type-text-with-summary field--label-hidden field--item"><p>One of the things about being a physicist that makes it tough to have any sensible work-life balance is that I'm constantly seeing little things and thinking "Oooh! Physics!" then getting distracted from what I'm actually supposed to be doing. Take, for example, our bathroom sink.</p> <p>I have noticed, from time to time, a weird effect where the stream of water coming out of the faucet, which normally is fairly straight, will spread out when the water level in the container below gets close to the faucet. This turns out to be damnably difficult to replicate, though, and I've spent more time than I care to admit screwing around with the sink trying to get it right. I finally got it yesterday, though, as you can see in this video (which also has a clip from a later failed attempt):</p> <iframe width="560" height="315" src="https://www.youtube.com/embed/yC8giHganmo" frameborder="0" allowfullscreen=""></iframe><p> And here's a couple of screencaps (also visible as the "featured image" above if you're not reading via RSS) showing what I'm talking about:</p> <div style="width: 610px;display:block;margin:0 auto;"><a href="/files/principles/files/2016/01/sink_stream_spread.jpg"><img src="/files/principles/files/2016/01/sink_stream_spread.jpg" alt="Two screencaps from the video showing the way the stream from the faucet spreads when water level of the container gets close to the nozzle." width="600" height="416" class="size-full wp-image-10514" /></a> Two screencaps from the video showing the way the stream from the faucet spreads when water level of the container gets close to the nozzle. </div> <p>On the left, the cup of water is lower down, and not completely full, and the stream from the faucet is basically straight, narrowing slightly. On the right, the cup's completely full, and close to the faucet, and you can see that the stream fans out just before it enters the water.</p> <p>The one semi-consistent thing I've noticed is that this seems to only happen with hot water; I've never gotten it to work with cold (the second clip is cold water, done deliberately to show that it's not a consistent thing). The flow rates in the two clips probably aren't identical, but that's a hard thing to match with the handles on our sink.</p> <p>Anyway, I have absolutely no idea why this happens; I'm mostly just glad to have evidence that I didn't imagine it. So I'm going to throw it out there and see if any of my wise and worldly readers can explain what the hell is going on.</p> <p>And now, actual work.</p> </div> <span><a title="View user profile." href="/author/drorzel" lang="" about="/author/drorzel" typeof="schema:Person" property="schema:name" datatype="">drorzel</a></span> <span>Mon, 01/25/2016 - 04:31</span> <div class="field field--name-field-blog-tags field--type-entity-reference field--label-inline"> <div class="field--label">Tags</div> <div class="field--items"> <div class="field--item"><a href="/tag/everyday" hreflang="en">Everyday</a></div> <div class="field--item"><a href="/tag/experiment" hreflang="en">Experiment</a></div> <div class="field--item"><a href="/tag/physics" hreflang="en">Physics</a></div> <div class="field--item"><a href="/tag/science" hreflang="en">Science</a></div> </div> </div> <section> <article data-comment-user-id="0" id="comment-1649098" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1453717639"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>It appears that your faucet aerator is one of those which doesn't emit water from the center, so that there can be a stable volume of not-mixed-with-water air inside the upper part of the stream. Notice how the uninterrupted stream has a sort of bulging shape to it which collapses a few inches down.</p> <p>I haven't seen the effect you're describing (and I don't currently have any of that type of aerator to test with), but I wonder if it has something to do with the hot water heating that air (which is presumably replaced by cold air drawn in at the aerator).</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649098&amp;1=default&amp;2=en&amp;3=" token="Jocfl54-Bir0do9a_eB9jQbSvk_RnkTkB94MO-BMXuY"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Kevin Reid (not verified)</span> on 25 Jan 2016 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649098">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649099" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1453721198"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>In the second case, the stream hits the surface sooner and won't build up as much speed so I think it is Reynolds number or something. A test would be to lower the filled cup to match the first surface height or vice versa. Clear glass would help see within the cup.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649099&amp;1=default&amp;2=en&amp;3=" token="hTl9LL1fVbVk-JmCOMi5VGohmngCvrhFGqM1wl9E6G4"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Lord (not verified)</span> on 25 Jan 2016 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649099">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649100" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1453723283"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>The transition between laminar and turbulent flow depends on geometry, so I wouldn't be surprised if there was a temperature effect as well. My guess is that the hot water case crosses the boundary into turbulent flow while the cold water case does not. And as Kevin notes above, it could be the air inside the water column that is crossing into the turbulent regime.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649100&amp;1=default&amp;2=en&amp;3=" token="N_p6545u4avkQn33Md4bCRnYuWQhykxr9VOgCIZ7NGU"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Eric Lund (not verified)</span> on 25 Jan 2016 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649100">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649101" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1453741169"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>I've seen similar things filling a bucket of water with a hose with a variable jet nozzle. At some hose settings there are two steady state solutions to the jet shape (compact or spread out). Also there is a distance from nozzle to water surface where the transition occurs, but this distance isn't the same if you are closing or opening the gap. In fact you can start with the open jet, stick it into the bucket, and pull it out with a compact jet even when its no longer hitting the bucket. To get it to spread again, requires changing the nozzle setting significantly.</p> <p> Obviously there is information flowing against the current, which I guess shouldn't be surprising as the sound speed in water is much faster than water jet velocity. But the fact that there are two stable configurations is interesting.</p> <p> Also a bit less mysterious is the hydraulic jump. Point the jet at a flat surface, near the center the flow is fast but thin, then some distance out there is a sort of shock front, beyond which the flow is thick and slow, and the transition is nearly wall of water like.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649101&amp;1=default&amp;2=en&amp;3=" token="B5KOraK17frhTZUtBhKT-bT1evSs5v9PbKUi6rim1tI"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Omega Centauri (not verified)</span> on 25 Jan 2016 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649101">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649102" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1453744790"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>Simple, slightly higher velocities and hot water draw in more air and the air is cooler than the water. The air expands as it heats and this combination causes the stream to bloom. </p> <p>At slower flows and with colder water it draws in less air and the air is cooled and contracts which means the stream narrows.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649102&amp;1=default&amp;2=en&amp;3=" token="niQzi72GT95MRg5WBi4EazG1aLR77zktpIoaSNxCqM8"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Art (not verified)</span> on 25 Jan 2016 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649102">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649103" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1453758981"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>I think Art has it. You're most likely far in the turbulent regime the whole time, in terms of Reynolds number, for both the air and the water (though two-phase flow is complicated). Regarding Omega Centauri's comment, see <a href="http://nanoscale.blogspot.com/2015/05/fun-with-fluids-hydraulic-jump.html">here</a>.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649103&amp;1=default&amp;2=en&amp;3=" token="MW28W6ve5l-J4s_kzSUlSsKjd56b5rCaXeDmeeJo_HI"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Douglas Natelson (not verified)</span> on 25 Jan 2016 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649103">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649104" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1453791237"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>Art, Douglas -- What explains the original observation, namely the relationship between the stream configuration and the faucet - water level distance?</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649104&amp;1=default&amp;2=en&amp;3=" token="bXlDidm0Ll13oF0OfhQYtlH-HqaUqdyYlkmSrifhPls"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Patrick Dennis (not verified)</span> on 26 Jan 2016 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649104">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649105" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1453910558"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>In the case when the water stream exhibits this widening phenomenon I believe there seems to be an air bubble blocked inside the stream. Upon close inspection, the center of the stream is more transparent than the sides, which indicates that the stream is "empty" inside (filled with air). When the phenomenon stops happening, the stream seems to be fully opaque.</p> <p>When there is an air bubble inside the stream and the cup moves closer to the faucet the bubble is forced to widen in order to maintain its volume. Of course it's widening more at the bottom (closer to the cup) because that's where the width is not constrained (as opposed to the faucet side, where the stream width is constrained by the faucet itself).</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649105&amp;1=default&amp;2=en&amp;3=" token="Y50a3GQsN1AMXqdqp6Sy8Fss48PcxQ4xb8xyd6rnAmg"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Balazs Vagvolgyi (not verified)</span> on 27 Jan 2016 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649105">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649106" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1454979553"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>Art has it.</p> <p>As for "closer or further away," the air bubbles trapped in the stream of water escape as a function of the length of the stream. When the stream is shorter, less air escapes, so when that column of aerated water encounters a closer surface, it tends to expand.</p> <p>And yeah, I also tend to see physics in everyday events. For example a small object that falls off a desk will always land in the location that requires the greatest expenditure of calories to retrieve, thereby maximizing thermodynamic entropy;-)</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649106&amp;1=default&amp;2=en&amp;3=" token="T3vx71Hc4CsgveBoCztMGPLPfpvxMlvFzb7MSRXGKb4"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">G (not verified)</span> on 08 Feb 2016 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649106">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649107" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1454979717"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>BTW my item in paragraph 1 of (9) is testable: find a small flat hard surface that can be placed under the water stream. I would expect that the water stream will expand as the object gets closer to the faucet, up to some point where a different set of dynamics takes over.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649107&amp;1=default&amp;2=en&amp;3=" token="1c25wiWQn17Itd7RF7dCDMIn3Q0xKabGn_17QRm3aA8"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">G (not verified)</span> on 08 Feb 2016 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649107">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> </section> <ul class="links inline list-inline"><li class="comment-forbidden"><a href="/user/login?destination=/principles/2016/01/25/fluid-dynamics-is-weird-bathroom-sink-edition%23comment-form">Log in</a> to post comments</li></ul> Mon, 25 Jan 2016 09:31:44 +0000 drorzel 49009 at https://scienceblogs.com Rotational Motion of a Bouncing Football https://scienceblogs.com/principles/2015/11/17/rotational-motion-of-a-bouncing-football <span>Rotational Motion of a Bouncing Football</span> <div class="field field--name-body field--type-text-with-summary field--label-hidden field--item"><p>I followed up <a href="http://scienceblogs.com/principles/2015/11/10/sports-technobable/">my ranty-y post about "Sports Science"</a> with an <a href="http://www.forbes.com/sites/chadorzel/2015/11/15/football-physics-checking-the-odds-on-wild-bounces/">experimental investigation</a> over at Forbes, tossing a football around on the deck out back and then doing video analysis of the bounces. This provided a wealth of data, much of it not really appropriate for over there, but good for a physics post or two here.</p> <p>One of the trajectories I looked at was this "forward bounce":</p> <iframe width="560" height="315" src="https://www.youtube.com/embed/5AJ2_FVYNoo" frameborder="0" allowfullscreen=""></iframe><p> Here's the trajectory reconstructed in Tracker:</p> <div style="width: 610px;display:block;margin:0 auto;"><a href="/files/principles/files/2015/11/sm_forward_bounce.jpg"><img src="/files/principles/files/2015/11/sm_forward_bounce.jpg" alt="Trajectory of a football bouncing forward." width="600" height="464" class="size-full wp-image-10365" /></a> Trajectory of a football bouncing forward. </div> <p>This is notable because not only does it bounce forward, it includes one of those big pop-up bounces that take people off guard. I <a href="http://www.forbes.com/sites/chadorzel/2015/11/01/football-physics-with-bonus-rugby-the-physics-of-bouncing-balls/">talked about this over at Forbes</a>, too, but it's nice to have a clear example.</p> <p>In that post, I asserted that the big bounce is a result of converting some rotational kinetic energy of the tumbling ball to center-of-mass kinetic energy. Which, of course, made me wonder whether you can clearly measure that in the video. You can, as it turns out, which is why I'm writing this post.</p> <p>What I did to make the above trajectory was to go through the video in Tracker and mark the center of the ball (the garish green laces on the black ball are well suited to this). To look at rotation, I put the same clip into Tracker, but instead of marking the center of mass, I made two trajectories, one for each end of the ball. That let me do a "relative position" of one end compared to the other, just by taking the difference between the measured positions. Actually, I get both a relative x and relative y coordinate, but this only needs one of the two; I used the vertical, because it's a little cleaner:</p> <div style="width: 610px;display:block;margin:0 auto;"><a href="/files/principles/files/2015/11/forward_bounce_rotation.jpg"><img src="/files/principles/files/2015/11/forward_bounce_rotation.jpg" alt="The difference between vertical coordinates for the two ends of the football, as a function of time." width="600" height="464" class="size-full wp-image-10366" /></a> The difference between vertical coordinates for the two ends of the football, as a function of time. </div> <p>This goes from positive to negative as the ball rotates, and you can clearly see the change in the tumbling at a time of just under 2s, when the big bounce occurs. The rotation period goes from roughly 0.21s to roughly 0.43s, corresponding to a rather substantial reduction in the rotational energy. About three-quarters of the energy that was in the spin of the ball gets turned into center-of-mass kinetic energy (and lost to thermal energy), which is why you get a big increase in the bounce height.</p> <p>You could probably do some more quantitative analysis of this, either using the mass and known shape of the football to estimate its moment of inertia and check the energy change, or using the change in the maximum height to estimate the change in potential energy and then work backwards to an estimate of the moment of inertia. These are both complicated by the energy loss on the bounce, and I'm home with a sick Pip today, so I'm not going to bother. Consider those extra-credit homework, if you like, and send your answers to Rhett Allain for grading.</p> <p>------</p> <p>The <a href="http://bit.ly/mysciblogreaders">science blog reader survey</a> I've been plugging at the end of my physics posts is coming to an end soon-- this Friday, in fact. It's part of Paige Jarreau's postdoctoral research on online communications, so please take a few minutes and respond-- it's for SCIENCE!</p> </div> <span><a title="View user profile." href="/author/drorzel" lang="" about="/author/drorzel" typeof="schema:Person" property="schema:name" datatype="">drorzel</a></span> <span>Tue, 11/17/2015 - 05:00</span> <div class="field field--name-field-blog-tags field--type-entity-reference field--label-inline"> <div class="field--label">Tags</div> <div class="field--items"> <div class="field--item"><a href="/tag/education" hreflang="en">education</a></div> <div class="field--item"><a href="/tag/everyday" hreflang="en">Everyday</a></div> <div class="field--item"><a href="/tag/experiment" hreflang="en">Experiment</a></div> <div class="field--item"><a href="/tag/physics" hreflang="en">Physics</a></div> <div class="field--item"><a href="/tag/science" hreflang="en">Science</a></div> </div> </div> <section> <article data-comment-user-id="0" id="comment-1649029" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1447760256"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>Nice example. This doesn't happen with a basketball because of its symmetry. </p> <p>This relates to spectroscopy...what frequencies are absorbed by certain molecules relates to whether they are symmetrical or not and what vibrational and rotational modes they have.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649029&amp;1=default&amp;2=en&amp;3=" token="_hXgmYQdeYwYfna7ru_MYlupnvmkka8yCjq6x-sIoBY"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Clay Blankenship (not verified)</span> on 17 Nov 2015 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649029">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> </section> <ul class="links inline list-inline"><li class="comment-forbidden"><a href="/user/login?destination=/principles/2015/11/17/rotational-motion-of-a-bouncing-football%23comment-form">Log in</a> to post comments</li></ul> Tue, 17 Nov 2015 10:00:30 +0000 drorzel 48955 at https://scienceblogs.com Energy Dissipation in a Physics Toy https://scienceblogs.com/principles/2015/11/05/energy-dissipation-in-a-physics-toy <span>Energy Dissipation in a Physics Toy</span> <div class="field field--name-body field--type-text-with-summary field--label-hidden field--item"><p>A little while back, I used a photo of SteelyKid's toy Newton's cradle as the <a href="http://scienceblogs.com/principles/2015/10/20/050366-physics-toy/">photo of the day</a>, with a bonus video:</p> <iframe width="560" height="315" src="https://www.youtube.com/embed/dysj3KJ2-qI" frameborder="0" allowfullscreen=""></iframe><p> I mentioned that I was going to do some analysis of this at some point, but didn't have time right then. I had a bit of time to poke at this yesterday, though, so here's some physics making use of the normal-speed part of that video (I have another purpose in mind for the high-speed stuff; you'll need to wait for that).</p> <p>The obvious thing to do with this is to plug it into <a href="http://physlets.org/tracker/">Tracker</a> and measure the position as a function of time. Here's a graph tracking the position of the two end balls through several bounces, mostly just because it looks cool:</p> <div style="width: 410px;display:block;margin:0 auto;"><a href="/files/principles/files/2015/11/newton_cradle_position.jpg"><img src="/files/principles/files/2015/11/newton_cradle_position.jpg" alt="The position of the two ends of SteelyKid's toy Newton's cradle." width="400" height="518" class="size-full wp-image-10322" /></a> The position of the two ends of SteelyKid's toy Newton's cradle. </div> <p>You can see the key behavior here, namely that the two alternate bouncing out really far, and also some real-world complication, namely the slight rebound motion of the two in between big bounces (this might be because I tugged it slightly to the side just as I started it, which made all the balls start swinging). But, like I said, it's mostly just a pretty picture.</p> <p>So, what's a more interesting physics question to look at? Well, the obvious departure from the perfectly ideal situation is that the balls don't keep bouncing forever, but slow down and stop. This happens because some of the energy of their motion gets shifted into other forms-- carried off by sound waves as the balls "clack" into each other, converted to heat that increases the temperature of the balls and the air around them, and converted into collective motion of all the balls together. so, how can we look at that?</p> <p>Well, the pendulum nature of the toy gives you a really nice way to monitor the energy content. At the extreme end of each swing, the full energy of the system is converted into gravitational potential energy of the ball at the end. That's simply proportional to its height above its stationary position (<em>U</em><sub>g</sub>=<em>mgh</em> where <em>g</em> is the strength of the gravitational field and <em>h</em> the maximum height reached by the ball of mass <em>m</em>). That maximum height is something I can read directly out of the Tracker files, meaning it's easy to make a graph of the energy content as a function of time.</p> <p>So, I measured the position of the ball on the right end of the toy at its maximum swing for some 68 bounces. The criterion for picking the frame with the maximum swing was to look for the least motion blur-- if my reflection in the ball was clear and sharp, that was the frame to use. I also measured the position of the end ball for four frames before the first bounce, and averaged those to get the zero position, which let me make this graph of maximum height as a function of time:</p> <div style="width: 610px;display:block;margin:0 auto;"><a href="/files/principles/files/2015/11/newton_cradle_energy.jpg"><img src="/files/principles/files/2015/11/newton_cradle_energy.jpg" alt="Maximum height of the right-hand ball (which is proportional to the gravitational potential energy) as a function of time." width="600" height="464" class="size-full wp-image-10324" /></a> Maximum height of the right-hand ball (which is proportional to the gravitational potential energy) as a function of time. </div> <p>(I could've converted the vertical axis to energy directly, but to do that I would need the mass of the balls, and that's annoyingly difficult to measure cleanly. So I'm being lazy and leaving it as height, which is proportional to energy.)</p> <p>As you can see, these trace out a very nice exponential decay function-- the solid line is an exponential fit, with decay constant of 0.103+/-0.002 1/s. That's a time constant of about 9.7s, if you prefer something you can easily compare to the graph.</p> <p>So, does it make sense that this should be an exponential? Well, an exponential function is sort of the default assumption for just about anything that decays-- there ought to be an "every decay is exponential" folk theorem in the same way that the Central Limit Theorem is semi-seriously used to justify fitting every distribution with a gaussian. But it does make a certain amount of sense-- the more energy in the motion, the more violent the collision, and the more energy goes into sound and heat and other dissipation. Which might lead you to conclude that the energy lost at each step should be proportional to the energy available, and if that's the case, you naturally get an exponential decay.</p> <p>Given that, I could reformulate this fit to ask how much energy is lost on each bounce. The graph that goes with this is basically identical to the one above, just converting the vertical axis to a percentage of the initial energy and the horizontal to bounce number. So, I won't bother putting it in the post, and will just quote the key result that the exponential decay constant is 0.063 +/- 0.001. Which corresponds to a loss of 6% of the energy with each measurement, or 3% per bounce (since there's one collision at each end between measurements of the maximum height). That's a number that seems pretty reasonable, though admittedly, I don't have a lot to base that on.</p> <p>So, there you go: a more detailed look at the physics of energy in a popular desk toy. As I said at the start, I have another plan for the high-speed portion of this, that I hope to reveal this weekend over at Forbes. While you wait for that, why not take a few minutes to <a href="http://bit.ly/mysciblogreaders">fill out the science blog reader survey</a> for Paige Jarreau's postdoctoral research on online communication? It doesn't take long, it's for SCIENCE!, and she's offering some cool giveaways. </p> </div> <span><a title="View user profile." href="/author/drorzel" lang="" about="/author/drorzel" typeof="schema:Person" property="schema:name" datatype="">drorzel</a></span> <span>Thu, 11/05/2015 - 04:16</span> <div class="field field--name-field-blog-tags field--type-entity-reference field--label-inline"> <div class="field--label">Tags</div> <div class="field--items"> <div class="field--item"><a href="/tag/everyday" hreflang="en">Everyday</a></div> <div class="field--item"><a href="/tag/experiment" hreflang="en">Experiment</a></div> <div class="field--item"><a href="/tag/physics" hreflang="en">Physics</a></div> <div class="field--item"><a href="/tag/playing-graphs" hreflang="en">Playing-With-Graphs</a></div> <div class="field--item"><a href="/tag/science" hreflang="en">Science</a></div> </div> </div> <section> <article data-comment-user-id="0" id="comment-1649004" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1446729364"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>Coefficient of restitution for steel spheres is in the high-ninties (Lifshitz, J. and Kolsky, H. (1964). Some experiments on anelastic rebound).</p> <p>The little rebounds naturally happen for the Newton's Cradle (though the magnitude of this may be affected by your push). It always spalls.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649004&amp;1=default&amp;2=en&amp;3=" token="KO-acIqif-Fm4Mvat5Uh0AzBKNJ1WfkIvQh-pwY2vXI"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">tcmJOE (not verified)</span> on 05 Nov 2015 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649004">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649005" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1446793347"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>The damped ossillator differential equation gives exponentiially decaying solutions. This isn't exactly a mass-spring-dashpot system but that's where I'd start to model it. I wonder how the packing or number of balls would influence the decay rate.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649005&amp;1=default&amp;2=en&amp;3=" token="eYYk0j4NygbNrXwW25kQ7OjsTlkt-Q_Qq0uuwI97Fyo"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Plebicus (not verified)</span> on 06 Nov 2015 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649005">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1649006" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1446797380"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>You might be interested in Mythbuster's attempt to scale up Newton's Cradle to wrecking ball size... see <a href="http://www.discovery.com/tv-shows/mythbusters/videos/newtons-crane-cradle/">http://www.discovery.com/tv-shows/mythbusters/videos/newtons-crane-crad…</a></p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1649006&amp;1=default&amp;2=en&amp;3=" token="AETyABKnDsFFYGwofbRg-fsSFhSwjqgCUZMlvhGgxrU"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">DomainRider (not verified)</span> on 06 Nov 2015 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1649006">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> </section> <ul class="links inline list-inline"><li class="comment-forbidden"><a href="/user/login?destination=/principles/2015/11/05/energy-dissipation-in-a-physics-toy%23comment-form">Log in</a> to post comments</li></ul> Thu, 05 Nov 2015 09:16:57 +0000 drorzel 48937 at https://scienceblogs.com Me in the Media: Two New Interviews https://scienceblogs.com/principles/2015/10/30/me-in-the-media-two-new-interviews <span>Me in the Media: Two New Interviews</span> <div class="field field--name-body field--type-text-with-summary field--label-hidden field--item"><p>I've been slacking in my obligation to use this blog for self-promotion, but every now and then I remember, so here are two recent things where I was interviewed by other people:</p> <p>-- I spoke on the phone to a reporter from <em>Popular Mechanics</em> who was writing a story about "radionics" and "wishing boxes," a particular variety of pseudoscience sometimes justified with references to quantum mechanics. The <a href="http://www.popularmechanics.com/science/energy/a17984/spooky-action-at-a-distance/">resulting story</a> is now up, and quotes me:</p> <blockquote><p> It is hard to investigate the ethereal thinking around radionics, but physics is something that can be parsed. So I got in touch with Chad Orzel, a physics professor at Union College in New York and the author of several popular science books, including How To Teach Quantum Physics to Your Dog. This sounded about my speed, and I ran a few ideas about physics and radionics past him, particularly "quantum entanglement," which several people offered as evidence that radionics is possible.</p> <p>"Entanglement is a very strange phenomenon," says Orzel. "But it's a very real thing."</p> <p>[...]</p> <p>"People try to invoke this as a way of justifying ESP sorts of things: 'Well, maybe electrons in your brain are entangled with electrons somewhere else.' There's a couple of problems with it," Orzel says. </p></blockquote> <p>You'll have to click through to see what the couple of problems are, though...</p> <p>-- A little earlier, Irene Helenowski <a href="https://helenowskiirene.wordpress.com/2015/10/23/interview-with-chad-orzel/">interviewed me by email</a>. This went live last week, when I was in California, which is my excuse for not posting it until now.</p> <blockquote><p> <strong>Professor, how is Emmy doing these days?</strong></p> <p>She's doing well. She's getting on in years for a dog-- she's 13-- so she's slowed down a bit. But she's still pretty spry, and can about pull me off my feet when she really wants to get to something on one of our walks. </p> <p><strong>You discuss simulating a black hole at CERN. What is the current status on the scientists' progress with that project?</strong></p> <p>It's not so much simulating, as trying to _create_ a black hole. The idea is that if you can pack enough energy into two colliding protons, you can create a situation where they get close enough together, and have enough total energy that they form a tiny black hole.</p> <p>This is very much a long-shot possibility at the energy of the actually existing LHC-- if nothing exotic is going on, there's no way the LHC energy is enough to make a black hole. There are some exotic theories where gravity gets dramatically stronger at short distances, though, and if one of these turned out to be true, there's a chance you could get a black hole. This would evaporate through Hawking radiation almost immediately, spraying out a burst of particles that could identify it as a black hole rather than a more typical collision.</p> <p>There have been some searches for this in data from the first LHC run, and no sign of black holes has been seen. They just recently re-started at a higher energy (by a factor of two, not enough to make mini-black-holes likely), and I'm sure there will be more such searches. Nobody really expects this to pan out, but it would be tremendously exciting if it did. </p></blockquote> <p>Again, click through to read the rest.</p> <p>------------<br /> And while you're clicking on things, please consider taking a few minutes to respond to Paige Jarreau's <a href="http://bit.ly/mysciblogreaders">survey of blog readers</a>. It's for SCIENCE!, specifically her postdoctoral research on communicating science online.</p> </div> <span><a title="View user profile." href="/author/drorzel" lang="" about="/author/drorzel" typeof="schema:Person" property="schema:name" datatype="">drorzel</a></span> <span>Fri, 10/30/2015 - 03:23</span> <div class="field field--name-field-blog-tags field--type-entity-reference field--label-inline"> <div class="field--label">Tags</div> <div class="field--items"> <div class="field--item"><a href="/tag/blogs" hreflang="en">Blogs</a></div> <div class="field--item"><a href="/tag/book-writing" hreflang="en">Book Writing</a></div> <div class="field--item"><a href="/tag/experiment" hreflang="en">Experiment</a></div> <div class="field--item"><a href="/tag/media-0" hreflang="en">In the Media</a></div> <div class="field--item"><a href="/tag/outreach" hreflang="en">Outreach</a></div> <div class="field--item"><a href="/tag/personal" hreflang="en">personal</a></div> <div class="field--item"><a href="/tag/physics" hreflang="en">Physics</a></div> <div class="field--item"><a href="/tag/physics-books" hreflang="en">Physics Books</a></div> <div class="field--item"><a href="/tag/publicity" hreflang="en">Publicity</a></div> <div class="field--item"><a href="/tag/quantum-optics" hreflang="en">Quantum Optics</a></div> <div class="field--item"><a href="/tag/relativity" hreflang="en">Relativity</a></div> <div class="field--item"><a href="/tag/science" hreflang="en">Science</a></div> <div class="field--item"><a href="/tag/theory" hreflang="en">Theory</a></div> </div> </div> <section> </section> <ul class="links inline list-inline"><li class="comment-forbidden"><a href="/user/login?destination=/principles/2015/10/30/me-in-the-media-two-new-interviews%23comment-form">Log in</a> to post comments</li></ul> Fri, 30 Oct 2015 07:23:30 +0000 drorzel 48928 at https://scienceblogs.com The Evolution of a Sad Balloon https://scienceblogs.com/principles/2015/10/19/the-evolution-of-a-sad-balloon <span>The Evolution of a Sad Balloon</span> <div class="field field--name-body field--type-text-with-summary field--label-hidden field--item"><p>A few years back, I did a couple of posts on the physics of a sad balloon (that is, a helium balloon that can no longer lift itself up to the ceiling), the first on <a href="http://scienceblogs.com/principles/2011/08/17/the-physics-of-a-sad-balloon/">simple buoyancy</a>, the second on <a href="http://scienceblogs.com/principles/2011/08/19/sad-balloon-physics-ii-how-lon/">how long it takes for the helium to leak out</a>. These were based on only a couple of data points, though, and it's always risky to extrapolate too far from just two points.</p> <p>Of course, in a house with two kids, we have helium balloons show up with some regularity, and SteelyKid's birthday this year provided a bounty of them-- four shiny Mylar balloons, bearing cheerful images of Scooby-Doo, some cartoon dinosaurs, Batman, and Pokemon. The Batman one was slightly larger than the others, and the Pokemon one was very quickly taken upstairs and tied to SteelyKid's door (so quickly, in fact, that it didn't make the photo with the others), where it suffered slightly less abuse than the other three, which were batted around every night until they deflated to the point where that wasn't fun any more.</p> <div style="width: 610px;display:block;margin:0 auto;"><a href="/files/principles/files/2015/10/sm_balloons.jpg"><img src="/files/principles/files/2015/10/sm_balloons.jpg" alt="Three of the four colorful Mylar balloons used in the experiment." width="600" height="400" class="size-full wp-image-10266" /></a> Three of the four colorful Mylar balloons used in the experiment. </div> <p>This provided an excellent opportunity for a longitudinal study of balloon evolution, as measured by lifting capacity. Roughly once a day, I would chain together a bunch of paper clips (the mass of 27 clips, as measured by SteelyKid's balance scale, was 9 grams, so a third of a gram per clip) and hang them from the balloon. Then I would remove clips from the chain until we achieved at least neutral buoyancy-- that is, if I moved the balloon down slightly, it would either stay where I released it or rise back up.</p> <p>So, what did I find? Well, it's not science without at least one graph:</p> <div style="width: 610px;display:block;margin:0 auto;"><a href="/files/principles/files/2015/10/balloon_evolution.jpg"><img src="/files/principles/files/2015/10/balloon_evolution.jpg" alt="Lifting capacity of our various balloons over time." width="600" height="464" class="size-full wp-image-10265" /></a> Lifting capacity of our various balloons over time. </div> <p>This shows the maximum weight supported (in grams) over a bit more than a month following SteelyKid's party. The longest-lived balloon was the Pokemon one that made it to relative safety upstairs (about 40 days before it couldn't lift a single paper clip), followed by the Batman one, which started with slightly more gas than the others. The Scooby-Doo and dinosaur ones took a pounding and succumbed relatively quickly.</p> <p>That's a much shorter lifetime than my estimate from 2011, which largely reflects the higher level of kid activity-- back then, The Pip hadn't yet been born, and SteelyKid was only three. With a three-year-old Pip and a seven-year-old SteelyKid in the house, the balloons absorbed a good deal more abuse.</p> <p>The one thing I found surprising about this was just how straight those lines are. I was kind of expecting to see some curving-- a more rapid drop at the start, when the pressure inside the balloon is higher, then a longer tail-- but these are pretty darn linear. On reflection, I think that makes sense-- while the initial pressure is clearly a bit higher than atmospheric pressure, it can't be a very big difference, and the final pressure can't be any lower than one atmosphere, so there's just not enough of a difference to change the rate. Thus, the helium diffuses out at a fairly constant rate, and these curves look straight.</p> <p>So, there you go, some birthday physics. For homework, estimate what pressure you would need to fill the balloons to in order for the helium to stop being a lifting gas, and speculate about what you might make such a balloon out of. Send your work to <a href="http://www.wired.com/author/rhettallain/">Rhett</a> for grading.</p> <p>------------</p> <p>I'm currently helping support a <a href="http://bit.ly/mysciblogreaders">survey of blog readers</a> as part of Dr. Paige Jarreau's research on science communication. If you read this or other blogs regularly, please take a few minutes and complete the survey. It's for SCIENCE!</p> </div> <span><a title="View user profile." href="/author/drorzel" lang="" about="/author/drorzel" typeof="schema:Person" property="schema:name" datatype="">drorzel</a></span> <span>Mon, 10/19/2015 - 03:59</span> <div class="field field--name-field-blog-tags field--type-entity-reference field--label-inline"> <div class="field--label">Tags</div> <div class="field--items"> <div class="field--item"><a href="/tag/everyday" hreflang="en">Everyday</a></div> <div class="field--item"><a href="/tag/experiment" hreflang="en">Experiment</a></div> <div class="field--item"><a href="/tag/physics" hreflang="en">Physics</a></div> <div class="field--item"><a href="/tag/playing-graphs" hreflang="en">Playing-With-Graphs</a></div> <div class="field--item"><a href="/tag/science" hreflang="en">Science</a></div> </div> </div> <div class="field field--name-field-blog-categories field--type-entity-reference field--label-inline"> <div class="field--label">Categories</div> <div class="field--items"> <div class="field--item"><a href="/channel/physical-sciences" hreflang="en">Physical Sciences</a></div> </div> </div> <section> <article data-comment-user-id="0" id="comment-1648958" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1445246831"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>Looks like a transcription error in the process description - "the mass of 27 clips, as measured by SteelyKid’s balance scale, was 27 grams, so a third of a gram per clip".</p> <p>Cool experiment.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1648958&amp;1=default&amp;2=en&amp;3=" token="jxkt26-JYqaAIipzirC6cobMCysZoYgSu0UN3OPbvuA"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Andy (not verified)</span> on 19 Oct 2015 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1648958">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="50" id="comment-1648959" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1445252245"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>An editing error; I started to put the mass and number in one order, then decided it would be better the other way around, and only half fixed it. It's fixed now.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1648959&amp;1=default&amp;2=en&amp;3=" token="iqdjOWNxcoxiRZboIvWvJJQNlEeCvAG8qGoidDGFYjM"></drupal-render-placeholder> </div> <footer> <em>By <a title="View user profile." href="/author/drorzel" lang="" about="/author/drorzel" typeof="schema:Person" property="schema:name" datatype="">drorzel</a> on 19 Oct 2015 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1648959">#permalink</a></em> <article typeof="schema:Person" about="/author/drorzel"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/author/drorzel" hreflang="en"><img src="/files/styles/thumbnail/public/pictures/after1-120x120.jpg?itok=XDhUCPqP" width="100" height="100" alt="Profile picture for user drorzel" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1648960" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1445290317"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>I read somewhere that helium is a non-renewable resource, and our descendants will curse us for wasting it on balloons for children. This did not stop me from inflating our remote control shark, but I wondered if you had an opinion.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1648960&amp;1=default&amp;2=en&amp;3=" token="eyEAXdNvKa1UcgAYm9enfIKd760x7JUfBKDYItNHatQ"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Beth (not verified)</span> on 19 Oct 2015 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1648960">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-1648961" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1445297412"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>Maybe try some rubber balloons for comparison? If the errorbars aren't too large, these might show the pressure-dependence better.</p> <p>I have one of these balloons in your image (not sure what they are called), it doesn't contain helium though, just plain old air. But the remarkable thing about it is that I've had it for 20 years and it still doesn't leak!</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=1648961&amp;1=default&amp;2=en&amp;3=" token="2NlY_PglSj9cjDPQoTFc7Dw5tuPdAP7d7vyPrPcx9ec"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Bee (not verified)</span> on 19 Oct 2015 <a href="https://scienceblogs.com/taxonomy/term/11536/feed#comment-1648961">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> </section> <ul class="links inline list-inline"><li class="comment-forbidden"><a href="/user/login?destination=/principles/2015/10/19/the-evolution-of-a-sad-balloon%23comment-form">Log in</a> to post comments</li></ul> Mon, 19 Oct 2015 07:59:08 +0000 drorzel 48913 at https://scienceblogs.com