Well, it was an unusual day here in Aspen. It was a day with lots of talks. Six of them, I think. There were four workshop talks scheduled for the morning, each of half an hour I think. Also got into a discussion before the sessions began, helping to explain how gauge/gravity duals work to a condensed matter colleague. I checked a voicemail message (only a relatively limited set of people have my number and so I figured it was a call to which I’d want to respond) and, despite the fact that I’m in retreat mode and would normally ignore it, returned the call. It was an office at USC wanting to put me in touch with a journalist who needed help. From Esquire. No, it is not what you think. I suggested they can could call me at 13:05, and at 10:30 went to the talks.
Somehow, successive speakers kept running over time due to lots of (actually, pretty interesting) interruptions and discussions, so I did not mind that we got to 12:50, and my talk, which was scheduled for 12:00-12:30, had not happened yet. With everything late, there was a decision by the organizers to have me speak after lunch instead. This left me with about ten minutes to wolf down my sandwich, since I had a phone call coming up. I’d have 25 minutes to field the journalist’s questions.
What did the Esquire guy want to talk about? Amusingly, the nature of time. Indeed, quite ironic. I first congratulated him on the idea to do the piece (it is connected to a fashion shoot involving timepieces), putting (as I love to see) science in unexpected places alongside other aspects of the general culture. Excellent.
In addition to the humourous “time is the thing that stops everything happening all at once”, remark that I could not resist making, we spoke at length about change, space, time, spacetime, the second law of thermodynamics, relative motion, time dilation due to relative motion, gravitational time dilation, the GPS system (and why it relies on the previous two things) and so on and so forth. Actually, it is in retrospect quite a bit of stuff to cover in 25 minutes. He was a smart guy, and I hope he got as much out of it as he said he did.
Then at 1:30 I gave my talk, which went well. People seemed to like it, and there was some excitement over the new vortex and droplet solutions Tameem and I found, and the discussion of where they fit on the superconductivity phase diagram. See here.
Then Allan Adams gave part II of a talk he started on Tuesday, followed by a colloquium at 3:00pm. Lots of good talks and great discussion today, but I’m exhausted! Going to relax with a novel for the rest of the evening, and get an early night. Tomorrow, I’m working head down, pen to paper. No talks for me.
-cvj
I can’t work out if this is a philosophical question or not. I will treat it as physics. The notion of field, whether you wsh to believe it is a mathematical device or physical entity, or whatever, is a very useful one that allows you to predict and explain many things in nature, in observation and experiment, to unsurpassed accuracy. So to that extent it exists. (And I know of no better way of establishing the existence of anything, to be honest.)
That is my best answer.
The nature of field and its various properties are well described in many sources on electromagnetism, on field theory and on quantum field theory. I can’t undertake to reproduce those discussions in a comment box. Suffice to say, the literature is rich and quite accessible.
Best,
-cvj
ok and how about the notion of field? We say that there exists an electromagnetic field. What I’m trying to ask is whats the nature of this field? is it just a mathematical device?
how does this field store energy? and how did the notion of permittivity (of free space) arise?
thanks.
Hi Kim,
I don’t understand what you’re saying here, but my main response is: why ask a string theorist? Some of them know, sure, but you can also (maybe better?) ask anyone who works with electrons directly, such as a condensed matter theorist. They deal with these things for their daily bread. For all intents and practical purposes, (and within the limitations of quantum mechanics, which you did not mention, but I’ll throw that in to be careful) the answer is simple. Yes. To a good degree of accuracy, for the right questions* I can say where an electron is and I can say when it is. So yes, it exists in space and time. The answer has nothing to do with fields, and indivisibility, and all that, as far as I can see.
Best,
-cvj
*See the uncertainty principle.
I once asked a string theorist if an electron exists in space and time and the answer given was yes. But when physicists speak of an electric field or an electromagnetic field of say an electron, we assume that the electron is an elemnetary particle which is indivisible. In what sense does it exist in space and time?
A field is represented by vectors no? so again, without a background in what sense can we represent this field?
Hi kim,
Excellent question. You’re very much correct. Actually, High Energy Physicists (myself included) study events closer to the Big Bang (and the event itself) precisely because it is a window on many of the same questions we ask about the nature and origin of the constituents of matter and force. These questions are all connected because the Universe today results from an earlier, high energy era when it was young. High Energy Physics is therefore imprinted on the Universe that is the subject of Cosmology and Astrophysics. It is therefore quite natural that this is so, and is one of the marvels of 20th (and post 20th) Century physics. [Actually, there were hints of this kind of connection earlier than the 20th Century too…]
Cheers!
-cvj
Dr. Clifford,
I have a very curious question to ask you. I wasn’t sure where to post but I will post here..HIgh energy physicists probe the atom at higher energies and seek to find how the 4 forces are unified. Astrophysicists consider events closer to the big bang. Is it not curious that whichever direction we go in (towards the big bang or towards the atomic scale) we are faced with the same questions?
For example the isnt the question as to how gravity fits into the picture at the atomic scale is the same as how it fits into te pucture near the big bang?