"The experiments that we will do with the LHC [Large Hadron Collider] have been done billions of times by cosmic rays hitting the earth. ... They're being done continuously by cosmic rays hitting our astronomical bodies, like the moon, the sun, like Jupiter and so on and so forth. And the earth's still here, the sun's still here, the moon's still here." -John Ellis
Relativity, or the idea that space and time are not absolute, was one of the most revolutionary and counterintuitive scientific theories to come out of the 20th century. It was also one of the most disputed, with hundreds of scientists refusing to accept it. Yet with less than $100 and a single day’s worth of labor, there’s a way you can prove it to yourself: by building a cloud chamber.
An old fishtank, some 100% ethyl or isopropyl alcohol, a metal base with dry ice beneath it and only a few other steps (see the full article for instructions) will allow you to construct a detector capable of seeing unstable cosmic particles. Yet these particles -- and you’ll see about 1-per-second -- would never reach Earth’s surface if it weren’t for relativity!
$100? Spendthrift. Why not just run a current through a pair of wires and watch as they attract (or repel) each other. Special relativity at work, as even the slow drift velocity is enough to unbalance the effective balance between the forces exerted by moving electrons and stationary protons.
I like this example, short clip, because it's high quality:
I had read somewhere that one time a reporter said to Einstein "There are hundred professors who say you are wrong."
Einstein answered "If I was really wrong just one professor would be enough."
was thinking of building a cloud chamber for years. It really is as easy as Ethan says. Just I can't get hold of dry ice for the life of me.
The only problem and why I gave up is that it's not really sustainable (other than hooking it up to a freezer). It only works as long as you feed it dry ice, or keep the temperature at some -10'C. Which is only about 15-20 minutes for DiY setup.
you don't actually need a cloud chamber (albeit it's simply cool), you can use your phone camera as a detector ;)
Just I can’t get hold of dry ice for the life of me.
PeaPod (Giant's on-line food ordering service) packs their frozen goods containers with dry ice. Big chunks of it, probably close to 6" or 8" square and 1" thick. I suspect (but don't know) that similar services like Amazon Marketplace would do exactly the same thing. So if you want dry ice, probably the easiest way to get it is to order a few gallons of ice cream online. You'll get your dry ice AND a tasty treat. :)
except I'm not in States :)
Dirty way is to use a CO2 fire extinguisher and blow the content into a sack.. Instant dry ice. :D But is a perfectly new fire extinguisher worth couple of minutes of watching cool stuff? .. mmm yeahh.. if someone else pays :D
Someone should invent a more practical cloud chamber similar to a plasma globe/lamp.
What, you barbarians don't have door to door bulk ice cream delivery service? You have to leave your couch to buy frozen food? No wonder the US is the only superpower. I pity you. :)
I've seen them being built with Peltier devices.. but again you end up with big rigs cause you have to remove the heat somehow and you end up with big alu heatsinks.
The ones that run on electricity with fans are about the size of midi desktop case.
I would love a silent cloud chamber the size of lava lamp i.e. In all honesty, it would be even a huge hit on crowd funding. I just don't think we're there yet with tech.
yeah... we actually have to burn some calories before we gain 3x as much :D But in all honesty.. no.. we don't have door to door bulk ice cream delivery service.. even without dry ice :D I can order ice cream from the store... with delivery.. but the state of it will be questionable :D We still don't realize we actually need ice cream in bulks :D
Everyone needs ice cream delivery in bulk. :)
The thing I miss from my science days is quick and easy access to liquid nitrogen. So much fun. If Giant ever starts using that for packaging somehow (and I have no idea why they would, so I'm not holding my breath), I'll start ordering food from them just to get the LN.
The most 'practical' example of relativity I find helpful (especially for the layman) is making people realize how bad the GPS on your cell phone would be if you didn't account for special and general relativity.
"The changes in time due to these properties of relativity total to an increase of about 38,700 ns/day and will conspire to make your GPS receiver build up errors in location that could cause it to be off on the order of kilometers after several hours—up to 10 km (6 miles) per day! The system is designed to correct for these errors by setting the atomic clocks on board the satellites to run slower than their corresponding reference on Earth before launch, so that once in orbit, and the effects of relativity take hold, the satellite’s clocks speed up and very closely match the reference on Earth. There are also corrections that are made to the satellite’s clocks to adjust for abnormalities in the satellite’s orbit that will cause their speed or altitude to drift over time."
About the muon argument for length contraction:
Those pesky little muons! They keep changing the depth of Earth's atmosphere. It's a wonder how airplanes can navigate through such an ever-changing depth of air. Not to mention... Earth's diameter keeps changing!
What new science is this in the last century? Science gone mad?
Hear hear, we have "for less than $100" the most powerful collider in the world, that helped us discover quarks etc. and figure out the whole Standard Model. What we see is what we got.
So why the heck keep on waisting energy on the LHC who is far less powerful knowing that we won't be able to squeeze anything unique discoveries out of it … the rabbit is out of the hat.
There's also a kit at Amazon for $38
" Dry Ice Required For Operation Not Included"
you get a Petri dish and a radioactive source. And you don't need a radioactive source if you want to catch cosmic rays. So you get a Petri dish for $38... not really a great buy.
Good that you read the details.
BTW in Europe you can buy dry ice for: 2,50 €/kg Tax incl.
The difference between the LHC and cosmic rays is luminosity. The LHC cannot produce energies as high as cosmic rays, but can produce collisions at slightly lower energies much more often than what can be observed by looking at cosmic rays. This is quite important because it's generally not sufficient to observe a collision or two to see what happens; it is often necessary to look at huge numbers of collisions to truly conclude anything.
Consider, as an example, a rather odd die. It has one hundred sides, but until it's rolled, you cannot see the markings on any of the sides. Once it's rolled, you can see the number marked on the top side. Suppose you want to study this strange die to see if the number 1 appears on any of its sides. Obviously, one roll is insufficient to conclude anything (unless of course you happen to roll a 1). If you don't roll a one, it's certainly quite possible that one of the other 99 sides does have a 1 on it. Even 100 rolls is insufficient; there is no guarantee you haven't rolled the same side twice. Each new roll without a one would increase the probability that no side has a 1 on it, but we could never be 100% sure that there is no 1 on any side. In order to be fairly confident in that conclusion, though, we could make a large number of rolls.
This seems contrived, but quantum interactions behave quite a bit like the die I described. We cannot gain any information about the state of a quantum system until we make a measurement. The measured value is an inherently random quantity. We cannot glean any information about what other measured values would have been possible after we've made the measurement.
Hopefully, the analogy is clear. When looking for a particular, theoretically possible, interaction arising from a particle collision at a given energy, it is not enough to observe one event. if we fail to see the proposed interaction, it's still possible that our theory is correct and the interaction could have occurred, but that just by chance it did not. The theory should also calculate a cross-sectional area for the interaction, which basically just gives the probability that the interaction will occur. Given enough chances for the interaction to occur, a negative result can rule the interaction out to a high degree of probability. Cosmic rays observations just cannot give enough opportunities for interactions to occur within any reasonable time span. The energy distribution is such that high energy cosmic rays exist, but are rare.
If it were possible, an observer living on the muon might well remark about how stupid humans are for thinking that the atmosphere really is hundreds of miles thick and that the earth is a sphere when anyone can see that the atmosphere is only hundreds of feet thick and that the earth is pancake shaped. You still haven't told me how you can determine which of these observers is objectively correct and which is objectively wrong.
I know you'll state that measurements made by commoving observers are the correct ones, but why should that be so? The same laws of physics apply and work well for both observers. Both observers make valid measurements. Obviously you are proposing something beyond measurement and beyond physical laws for determining who's right and who's wrong. What is it?
Thanks for your explanation, but my comment was more directed at the argument that the LHC is (possibly) going to find 'new physics'.
Sure something 'new' might surface but it won't be anything spectacular, if there would be anything 'amazing' it would have already shown up in a cloud chamber.
It is not like the Hubble telescope that gave us sharper images, and a clearer insight, seeing what no one has seen before, the LHC more about categorizing better what we already have seen. It's not revolutionary.
Sean T @ # 19:
" Obviously you are proposing something beyond measurement and beyond physical laws for determining who’s right and who’s wrong. What is it?"
Yes, beyond measurement, but, no, not beyond physical laws.
Yes, all "things" exist with all their intrinsic properties whether or not they are measured. They are created and exist by natural forces which can be described by physical laws.
The laws of physics are the same for all things. Theories and measurement come after, as we try to understand the real physical world. (Yes it exists independent of all science.)
Yes, all “things” exist with all their intrinsic properties whether or not they are measured. They are created and exist by natural forces which can be described by physical laws.
This quite literally doesn't mean anything, just like your invocation of the word "entity."
^ Oh, right: So, being measurable* is only a sufficient but not necessary aspect of a "real" "entity"? Let's review:
Ontology is the study of “What it is” in the real world. It assumes a real world. This is based on the fact that a real world must exist before it can be observed or measured in any way.
I foolishly wasted time writing more here, but I now see that you've run into this whole self-contradiction problem before in the over six years that you've been trotting out exactly the same dreck: htp://www.scienceforums.com/topic/20069-relativity-of-motion-discussion-from-….
* This word is graced with scare quotes in a comment above the one linked.
"but I now see that you’ve run into this whole self-contradiction problem before..."
Then he never actually went out of it, in the first place. Whack for 6+ years and counting.
had to put this up
Grammatical variants of the term ‘observation’ have been applied to impressively different perceptual and non-perceptual process and to records of the results they produce. Their diversity is a reason to doubt whether general philosophical accounts of observation, observables, and observational data can tell epistemologists as much as local accounts grounded in close studies of specific kinds of cases. Furthermore, scientists continue to find ways to produce data that can’t be called observational without stretching the term to the point of vagueness.
It’s plausible that philosophers who value the kind of rigor, precision, and generality to which l logical empiricists and other exact philosophers aspired could do better by examining and developing techniques and results from logic, probability theory, statistics, machine learning, and computer modeling, etc. than by trying to construct highly general theories of observation and its role in science. Logic and the rest seem unable to deliver satisfactory, universally applicable accounts of scientific reasoning. But they have illuminating local applications, some of which can be of use to scientists as well as philosophers."
I'm still marveling at the wrongness of this:
Ontology is the study of “What it is” in the real world. It assumes a real world.
How somebody could prattle on for years and years about ontology and not understand the plain meaning of the word (hint: monist idealism is an ontological stance) utterly defies my comprehension.