What is Time and Space

Penrose is the greatest mathematician alive (in my eyes).
His perspectives on Quantum Physics in "The Road to Reality" really opened my eyes.Especially the perspective of approaching Quantum Gravity from a relativists point of view, instead of a QFT point of view.(Not to say that a relativistic approach is better, just that I've never seen it before).cavediver, what is part III like in Cambridge?
I've always been tempted to do it.

I just want to be sure on what you're saying here.Let's just take the evolution of a single species.
Let's say from a fly with a feeler to a fly without a feeler.If one considers evolution from a "Block Time" point of view all you have is a 4-D "shape". A 3-space slice of which, at one end looks like a population of flies with a feeler and, at the other end, a population of flies without a feeler.You would feel something is missing?

At least to my eyes, Oxford and Cambridge have a older and more pronounced culture of "learning for the sake of learning" in the sciences. They're one of the few universities where physics doesn't have a utilitarian edge to it.Even if you look at the undergraduate courses, they're far more "fluid" in what a student is allowed to do.

Sorry to ask something off topic, but I heard today that in String Theory one considers the coupling constant as a dynamic field. Rather than just a variable which depends on the energy scale.
Is that true?Edited by Son Goku, : Clearer message title.

I personally don't know much about Barbour's theories, but ideas similar to this already occur in physics.
For instance in the path integral approach one sums over the different paths a particle can take between point A and point B to obtain the the amplitude (which is squared to obtain the probability) for the particle to go from A to B.Each path is essentially the path the particle would take in a world with different laws of classical mechanics.
You don't assume this though, it follows from other things in QM.
It is a different calculational technique with an unusual picture associated with it.In essence they aren't really other universes, it's just that one can consider a quantum mechanical process in our quantum mechanical universe as a weighted sum of classical processes from slightly different (and continously different) purely classical universes.Barbour's idea probably contains a similar idea of "universe".Edited by Son Goku, : Slight edit and expansion.

I assume you know what Energy is.Now for work:
Work is basically Energy by distance, the amount of effort it takes to move across a distance.
Action is basically Work by time or "Energy by distance by time", the amount of effort it takes to move a distance x and through a period of time t.One of the axioms of classical mechanics is that, for any system, the action takes the smallest possible value it can.
A little more formally the Principle of Least Action (for most systems) states that the difference between Kinetic and Potential Energy is kept to a minimum.
This is called the principle of least action, made famous by the physicist Hamilton.
(Who used the walk the canal behind the house that I grew up in.)Edited by Son Goku, : SpellingEdited by Son Goku, : Expansion.