Newton's law of conservation as it applies to the big bang

[OryHaram]

I had a thought the other day and I am looking for someone to tell me why it does not work.

In consideration of energy be neither created nor destroyed, to me this would say there is not enough energy to continue expanding the universe.

I also make the conjecture the gravity never stop effecting any or everything else in the universe, similar to quantum entanglement.

Any thoughts?

 

[Drakkith]

In consideration of energy be neither created nor destroyed, to me this would say there is not enough energy to continue expanding the universe.

Conservation of energy doesn't apply to the universe as a whole, since there is no way to unambiguously define the total energy of the universe under General Relativity. See here: http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html

I also make the conjecture the gravity never stop effecting any or everything else in the universe, similar to quantum entanglement.

Quantum entanglement and gravity are nothing alike, but you are correct about gravity in the sense that gravity's range is infinite.

 

[bhobba]

Just to expand on Drakkiths excellent reply you have to understand the modern view of energy conservation. It actually follows from a very profound theorem called Noether's Theorem:
http://math.ucr.edu/home/baez/noether.html

The history behind it is both interesting, instructive about the climate for female students at the start of the last century, and explains why energy conservation does not apply to the universe as a whole:
https://arstechnica.com/science/201...-the-course-of-physics-but-couldnt-get-a-job/

To sum up because space-time is curved the symmetry required for energy conservation does not exist so even the concept of energy is up for grabs in GR as explained in the link Drakkith gave.

Putting my mentors hat on I want to mention personal theories are not allowed on this forum. I know you just mentioned a conjecture in passing, however in the spirit of our rule against personal theories if you can resit the urge in future it will make it easier for those following the thread - they will not be distracted by side issues.

Thanks
Bill

 

[PeterDonis]

because space-time is curved the symmetry required for energy conservation does not exist

Just to be clear: it's not the fact that the spacetime of the universe is curved; it's the fact that the spacetime of the universe does not have any time translation symmetry. There are curved spacetimes that do; but the curved spacetime that describes our universe is not one of them.

 

[OryHaram]

Thank you for the replies, I only meant to say that like entanglement it would have no range.

 

[Drakkith]

Just to be clear: it's not the fact that the spacetime of the universe is curved; it's the fact that the spacetime of the universe does not have any time translation symmetry.

Have any links that elaborate on this but aren't quite graduate-textbook level?

 

[PeterDonis]

Have any links that elaborate on this but aren't quite graduate-textbook level?

Sean Carroll discusses it some here:

http://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/

He says "time translation invariance" instead of symmetry. The basic point is that the expansion of the universe breaks time translation invariance.