How real scientists react to General Relativity being trillions off in a prediction

Wyclef on 6/4/2006 at 03:55

Coincidentally, today I talked to Frank Wilczek, who was awarded the 2004 Nobel Prize in Physics for asymptotic freedom.

<3 <3 <3

I'm a CM guy (but I'll get to QFT in a few years), but it's my understanding that simple analytical expressions can't be written for the strong force because of the way the interaction scales with energy as determined by renormalization. Asymptotic freedom is the phenomenon of coupling parameters going to zero as energy becomes large.

I almost went into computational QCD -- particularly, exploration of the properties of quark matter -- but I hesitated, partially because I realized it wasn't the greatest career move. :erg:

As a CM person, I don't know all that much about the SEXEH topics in physics like OOO STRING THEORY. If any of you FAGS want to discuss statistical mechanics, though...

TheGreatGodPan on 6/4/2006 at 04:30

Quote Posted by Wyclef

it's my understanding that simple analytical expressions can't be written for the strong force because of the way the interaction scales with energy as determined by renormalization.

I find that oddly calming. I was really getting bugged, like when someone walks up and says "I've got this really great secret and I'm never going to tell you", then laughed and walked away, and then you try to beg, cajole, convince and threaten them to spill the dirt but they just keep rubbing it in your face and before you know it you're not allowed to attend that kindergarten anymore.

Quote Posted by Wyclef

I hesitated, partially because I realized it wasn't the greatest career move. :erg:

What are you planning on doing when you finish your studies? If you're rather confident in the bright future ahead of you, you might find (http://wuphys.wustl.edu/~katz/scientist.html) Don't Become a Scientist! amusing. Otherwise it might be depressing.

With regards to string theory, I've seen stuff like elegant universe, but its always just "There's these tiny vibrating things called strings and extra dimensions and multiple universes and everything we know might be wrong, get back to you when we're able to detect anything at this scale!". Kind of interesting but I didn't feel my grasp of physics really improved. Maybe I had to be a lot more knowledgeable to begin with for it to matter, like how attending a lecture in Farsi isn't going to enlighten you much (assuming you don't speak it).

Wyclef on 6/4/2006 at 04:43

Quote:

I hesitated, partially because I realized it wasn't the greatest career move. What are you planning on doing when you finish your studies? If you're rather confident in the bright future ahead of you, you might find Don't Become a Scientist! amusing. Otherwise it might be depressing.

Yep, I read that a few months ago. Perhaps it would have been more useful a few years ago, but at least I was already reconciled to the fact that the academic job market is generally dismal. However, I tentatively plan on getting, along with the PhD in physics, an MS in Finance, as the mathematics dovetails nicely with the mathematics of stat mech (one popular book is titled <i>A Random Walk Down Wall Street</i>) and because Wall Street has a decent number of six figure jobs available for quants. It helps even further that I'm in all probability doing my thesis in computation -- quants do computational modelling. In fact, (http://guava.physics.uiuc.edu/~nigel/finance.html) UIUC makes getting an MS/PhD rather easy.

I pretty much ruled out doing High Energy theory or string theory because the market in those areas is particularly bad, and because I'd rather not compete with Wunderkinder who were doing contour integrals in the womb. Condensed Matter comprises some 60% of the publications in Physical Review, it has relevance to industrial application, etc.

descenterace on 6/4/2006 at 06:34

Quote Posted by demagogue

Not exactly like any other force the way I learned it. The first thing my teacher said about gravity: it's not a force. Everything can be explained using curved geometry without having to have anything "pushing/pulling" anything else.

When you are in free fall, you don't feel any accelleration ... so if you were in a falling elevator, you wouldn't even know it from being in space. But if you were being pulled by a magnet (or presumably the weak or strong force), you'd feel the accelleration (right?).

Three words: frame of reference. Your environment is falling as fast as you are.
Also, gravity is operating on every part of your body at the same time, inside and out, so you don't feel like you're being 'pulled' anywhere. If you were made of iron, the magnet would be operating on you in much the same way, but don't forget tidal effects...

Close to the magnet, there would be an appreciable difference in strength of field over a distance of a couple of centimetres. So you would feel as though you were being stretched. Close to a large source of gravity you'd get the same effects, but we don't notice them here on Earth because we're actually a very long way from the centre of the planet. Crush the mass of Earth into a space the size of a car and you sure as hell would notice it.

Quote Posted by demagogue

So it's a lot like the other forces, but it's always the odd-ball out.
By the way, can anyone explain why gravity is so odd compared to the other forces? I've heard different things, but was always curious.

Nope, it's no different from electromagnetism or either nuclear force except in that gravity is a property of mass. Gravity is the weakest force, but reaches furthest.

TheGreatGodPan on 7/4/2006 at 00:35

Quote Posted by descenterace

Nope, it's no different from electromagnetism or either nuclear force except in that gravity is a property of mass. Gravity is the weakest force, but reaches furthest.

Gravity and electro-magnetism both decrease with the square of the distance, but there isn't usually a big net charge, whereas all mass adds together as a positive (or negative, point is its all the same sign with no cancelling out).

That reminds me. I'd once heard that strong & weak were supposed to have NO strength at all beyond some distance. Do their force particles decay too fast or something? Or are tehy just continous functions of distance that limit to about zero like the others but much quicker?

BlackCapedManX on 7/4/2006 at 01:21

Quote Posted by TF

what

Nothing moves faster than light. If the sun vanished, it'd take a pretty large amount of time before our orbit would gonk.

Um.... don't quantum jumps occur with no intermediate stages and quantum states in entangled particles "teleport" instantly?

If so that would be faster than the speed of light (infinitely faster infact), and would also be much more suitable for deep space communication.

Wyclef on 7/4/2006 at 01:54

Quote Posted by TheGreatGodPan

That reminds me. I'd once heard that strong & weak were supposed to have NO strength at all beyond some distance. Do their force particles decay too fast or something? Or are tehy just continous functions of distance that limit to about zero like the others but much quicker?

Like I said, I don't know many details, but it's worth noting that 1.) the justification for the exponential decay of the Yukawa potential is the decay of the force carriers, because they're massive, and 2.) since the strong force only increases as you try to pry quarks apart, at sufficiently large distances that energy is converted into mass, anyway, and you just end up with two hadrons instead of one.

Quote:

1.) Energy-time uncertainty, deltaE*deltaT ~ hbar

Aside from that, the only way you can stimulate emission (and therefore transmit information) is with photons of a suitable frequency distribution, and those travel at c. (Spontaneous emission is just emission stimulated by the quantum vacuum)

2.) Collapse across space-like intervals can be interpreted as an instantaneous "cause" of a sort, but it's not a real cause in that it cannot transmit information.