Universe smaller than wavelengths?

[kashiark]

How did particles exist in the very, very early universe when its diameter was smaller than their wavelengths? Are we just supposed to be content with the supposition that wave descriptions are impractical in this situation?

 

[Dmitry67]

I believe you are talking about the observable universe.

I discussed it here:
https://www.physicsforums.com/showthread.php?t=371333

so correct, it early Universe only short wavelengths were allowed, hence particles were very hot. I looked at it from E and t as non-commuting variables, you - from p and maximum size.

 

[Galap]

How did particles exist in the very, very early universe when its diameter was smaller than their wavelengths? Are we just supposed to be content with the supposition that wave descriptions are impractical in this situation?

As of now we have no theory that describes the very early universe. All our current theories run into big problems there. Are we supposed to be content with it? No. That's what physics is all about: figuring it out, coming up with a theory that accurately describes these things.

 

[Dmitry67]

We don't have quantum gravity theory yet,
so the semi-classical approach is the best we can do