Todays Physics Puzzles

[kamil]

Hey, im just curious on what are todays puzzles/paradoxes/mysteries in theoretical physics. I already know that there is the search for the Unified theory.
I have also heard that there is a contradiction between GR and QM, can someone please explain this in simple terms.
And can you please list any other problems that the leading theoretical physicists are currently working on. I dont want to get the idea that physics is 'complete' because i know from reading Max Planck's biograghy to not think like that.

Thanks in Advance, Kamil.

[Jay-qu]

I dont know about a contradiction but GR has smooth continuous spacial fabric while QM on a very small scale (sub plank length) is chaotic and not smooth at all. One way this is rectified is bringing in strings which have a very small but finite length that does away with point particles and hence smoothing out the bumps in QM.

Problems, I would say blackholes still hold some mystery, and I would like to see gravity defined more definitly

[Qfwfq]

Originally Posted by Jay-qu

QM on a very small scale (sub plank length) is chaotic and not smooth at all.

Actually, this is a consequence of considering gravity in QM. Considered separately, the two don't run into trouble, x and t have continuous spectra in basic QM.

[Jay-qu]

Originally Posted by Qfwfq

Actually, this is a consequence of considering gravity in QM. Considered separately, the two don't run into trouble, x and t have continuous spectra in basic QM.

ok, i see.. but can you consider them seperately and get correct results? how is this different from when they are combined ..

[Qfwfq]

Originally Posted by Jay-qu

ok, i see.. but can you consider them seperately and get correct results?

Yes, a lot of correct results have been obtained, at whopping huge scales of distance... I mean, greater than several Planck lengths.