Ask Me Stuff

Hi Chad

If gravity has a particle nature & is limited to light speed, how is it that the mass that has disappeared inside the horizon of a black hole still communicates its 'weight' to the outside universe? I am a layman so go easy on my stupid question :)

Please write about the implications of Renninger-style "null measurements" (failure to obtain detector click means the particle "now has to be somewhere else".) This leads to the odd concept of "reallocation" of the wavefunction, a partial collapse in effect, instead of total collapse to one spot. Furthermore, what if a detector is unreliable? (Well, really all of them are!) This goes beyond Renninger: if it clicks, or not, that doesn't prove that the particle was there or not for sure. So what happens to its WF? Thanks.

Another scientific explanation of a commonplace phenomenon, like the one you did with the balloon, please!

What is the fine structure constant?

Can you post some photos of your lab and the lab equipment? I haven't been in a physics lab in about 20 years, and I'm curious to see some of the things research scientists are doing.

What's the deal with quantum computing? How is it "quantum", how is it different from ye olde Turing machine, and when will it be ready for prime time? Should people be paying more attention to it than they are?

postulate - a "mind experiment"

where the speed of light varies with the effect of gravity

such that it could provide a different explanation for red shift

ie imagine that light traveling in intergalactic space (where we can't measure it) is traveling faster than our measured constant - and that as it enters our galaxy (more gravity) it slows down

show how such a construct might explain some of the currently unexplained observations

if there are holes in the idea - make up answers to explain them - run the mind experiment as far as it can go before collapsing

thanks

pop

I'd like to hear more about your class on time and timekeeping. How well do you think students learn the big ideas about how science works from these classes, as apposed to a more traditional general physics class? How much transfer do you see in students' understanding of the content of this course to understanding of science in general?

Do we know that gravity causes time dilation? Could time dilation cause gravity, or could both be independent side effects of being near a large mass?

Physics of swings (i.e., the playground equipment beloved of young children)! How is it that simple wiggling about on the end of the pendulum induces it to swing ever higher?

Chad, my question is, "What's the inconvenient policy change?"

Darn. From time to time I think of a question I wish I could lob your way, but don't know your email address and don't want to ask an irrelevant question on an unrelated blog post. Of course, now I can't think of any.

Could we get a few pictures of Emmy, sometime?

Actually, if you can explain SPIN to your dog a lot of people would appreciate it. I've tried reading E. Cartan, and H.A. Kramers QM and he seems to do a pretty decent job of it. I even tried looking up the original Heisenberg-Jordan paper on it, but it does not seem to be available online. But for something so darn fundamental it sure is confusing. And if it is so quantum mechanical, then how did Thomas get away with a more or less Classical analysis and fix the factor of 2 ? Dirac fixed all that, but everybody goes on about predicting antimatter instead of clarifying spin. How a muon and an electron can have the same intrinsic angular momentum does not seem to be on a list of unsolved problems.

Lower level than the other questions but: I just finished teaching freshman calculus. What do you desperately hope I told my students?

I've got one for you, or the commentariat at large: What are your views on professional societies?

I ask because despite being in D.C. for the last four years, I haven't joined any - in fact the last thing I was a member of was the Society of Physics Students as an undergrad. Now that the postdoc is winding down, I get the nagging impression that joining one or two might help, but their membership benefits are all vague and I can't shake the suspicion that I'd be paying a decent chunk of money solely to put my name on a host of annoying mailing lists. So, what sort of benefit do you get from these organizations, and is it worth it in these days of social networking and an almost limitless number of specialized conferences to present at?

What's the biggest (most prevalent or most pernicious) misconception that you feel the general public* has about physics? (*or other scientists - you can gripe about chemists, biologists, geologists, etc. if you want)

Is there a physics principle/result that you think is unappreciated by the general public? Is there one you think is unappreciated by *physicists*?

If there is one thing that you would like to seen done to improve the science/physics literacy of the general public, what would that be?

What advice would you give to high-school Chad (or undergrad/grad student/postdoc Chad)?

Does Emmy prefer head rubs or tummy rubs?

Is there an upper bound on the energy of a single photon? And how would one go about measuring such a very high energy photon?

A 300mm lens on a canon 7D is 480mm so why is a 1.4 teleconverter on the same camera setup only 420mm? It does not make sense. What is the real convertion size?