Universal Constants (Umbran, Pbartender)

[Michael Morris]

How much progress have we made in determining why the universal constants (speed of light, absolute 0, etc) are what they are? I know it's a bit of a 5 year oldish question, but I am curious about it. (This is mainly aimed to Umbran & Pbartender - our resident physics PhD's, but open to anyone else I don't know about willing to ponder a moment).

 

[der_kluge]

The answer is 42. Everyone should know that by now.

 

[jgbrowning]

Of course. And the Question is, "What is 6 times 9?"

joe b.

 

[Michael Morris]

kludge> Say wha???

 

[Ycore Rixle]

I'm sure the PhD's can contribute a lot more than I can, but basically I believe the answer is: "not much." The big question is about the cosmological constant, which is a leading candidate to explain the accelerating cosmic expansion of the universe. Lee Smolin and Leonard Susskind have a famous debate about cosmological natural selection and the anthropic principle that is posted pretty completely here: http://www.edge.org/3rd_culture/smolin_susskind04/smolin_susskind.html
And Lawrence Krauss and someone (Mike Turner?) have a good article on it in a Scientific American from last fall, I think, titled "A Cosmic Conundrum."

Basically, what's causing the accelerating expansion, why the vacuum energy density is what it is instead of something absurdly high while still not being exactly zero, is a wide open question. String/M theory appears to predict a whole "landscape" of possibilities for the constants, and why we're in a universe with the properties that we observe, well, if I understand correctly, that's the whole rub. No one knows.

Arxiv.org is always interesting for papers too, although they're pretty tough to understand sometimes.

So yeah, no definitive answer, as far as I know. But as I say, one of the PhD's will surely know more.

 

[tarchon]

It depends on the constant. Some are well understood, some aren't, but there's always some irreducible quantity back there somewhere.

 

[fuindordm]

None, really. Some versions of string theory promise to show that the fundamental constants are related, but the math is too complicated for this theory to take us far right now.

The masses of particles are thought to be determined by their interactions with a ubiquitous field of Higgs bosons, which have not yet been detected. Physicists have high hopes that the Large Hadron Collider at CERN will confirm this theory when it's completed.

The philosopher-physicist's answer would be that if the universal constants were much different from what they are observed to be, then the universe would not have been able to create life like us. A small tweak to the gravitational constant or electron properties, for example, would result in star lifespans too short to support planetary systems, or too long to have created heavy elements. A certain amount of fine-tuning appears necessary right now to form a universe like ours.

There are two schools of thought: either we'll eventually be able to show that the universal constants are as they are because it's the only possible consistent configuration given some simple assumptions about the nature of the universe, or that universes of all kinds are being created all the time, and only those capable of creating conscious observers will be observed (the weak anthropomorphic principle)

Ben
(an astrophysicist)

 

[Pbartender]

First... I think this is the very first time in the 5 years I've been floating around the boards that someone has specifically asked around for me in a thread title. I'll have to celebrate.

How much progress have we made in determining why the universal constants (speed of light, absolute 0, etc) are what they are? I know it's a bit of a 5 year oldish question, but I am curious about it. (This is mainly aimed to Umbran & Pbartender - our resident physics PhD's, but open to anyone else I don't know about willing to ponder a moment).

Second, I'm not actually a Physics PhD, though I'm humbled and flattered that you think so.

On to the question!

Why are Universal constants are what they are? We know exactly why they are...

Base 10 mathematics, arbitrarily defined units of measurement and carefully measured and calculated ratios of observable phenomina. If humans had a dozen fingers and toes instead of ten, or if a meter was only twice as long as a foot, most numerical constants would have much different numbers.

That said, constants are constant, no matter how you measure it, it doesn't change. Why does it happen to be the specific value it is? Well, because that's the way the unvierse works. Figure that one out, and they give you a Noble Prize and the choice between the red pill or the blue pill.

Your question is probably better suited for a Philosopher to answer. Remember, science is a lot more about the hows than the whys. To put it into EN World terminology... It's the Scientist's job to figure out what the rules of the game are. Engineers come up with ways make those rules work to our advantage. And Philosophers argue about whether or not the rules are fair.

 

[Ankh-Morpork Guard]

That said, constants are constant, no matter how you measure it, it doesn't change. Why does it happen to be the specific value it is? Well, because that's the way the unvierse works. Figure that one out, and they give you a Noble Prize and the choice between the red pill or the blue pill.

This is the first time I've ever really wanted to .sig a quote from someone on the boards.

 

[Michael Morris]

heh heh yup. Good answer pb, good answer.

So in gamer terms
scientist = neophyte
engineer = power gamer
philosopher = rules lawyer

right?