Is my reasoning correct? Energy "before" the big bang?

In summary: How is this possible? Wouldn't that mean nothing can happen?Energy is conserved in closed systems, but it doesn't mean that nothing can happen.There is a possibility that E2=0. See Lawrence Krauss' book "A Universe from nothing", for example.
  • #1
toothpaste666
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It seems as though that according to conservation of energy, there could never have been a point in the timeline of the universe where nothingness existed. It seems to me that the claim that there was nothingness before the big bang would violate these laws. For example if E is the total energy of the universe then the law states that E = constant. If E1 is the total energy of the universe at an arbitrary time t1 and E2 is the total energy of the universe at arbitrary time t2 , then E1 = E2. let's say t1 is before the big bang and t2 is right now. If there was nothingness before the big bang, then E1 = 0. Since right now it is obvious that E2 > 0 , or , E2 != 0, then E1 != E2 which would violate conservation of energy. Is this line of reasoning correct? if not, why?
 
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  • #2
Without a universe, there is no conservation law a big bang could violate. "Before the big bang" is meaningless if the universe started with it, and you cannot assign an energy to something that does not exist.

By the way: general relativity does not have global energy conservation.
 
  • #3
Conservation of energy arises due to the time translation symmetry of the laws of physics (see Noether's theorem).

Our current theories say that there is effectively no time before the Big Bang (in the geometric sense that one cannot go further north than the North Pole). If that's true, then one simply cannot translate from the Big Bang further into the past and say the laws of physics remain invariant.

If there is no time translation symmetry at the point of the Big Bang, there is likely no conservation of energy (as we know it) either.

At least currently, we can only speculate about what the laws of physics were like before the big bang (if there even was a "before").
 
  • #4
mfb said:
By the way: general relativity does not have global energy conservation.
Is that not what "dark energy" and the "cosmological constant" is for?

Time translation symmetry is certainly a tricky thing in general relativity, but is there really no workaround?
 
  • #5
jfizzix said:
Is that not what "dark energy" and the "cosmological constant" is for?
No. There is no unique meaningful way to define "the energy of the universe at a specific point in time", and as far as I know no matter how you define it there is a process that could change it.
 
  • #6
toothpaste666 said:
It seems as though that according to conservation of energy, there could never have been a point in the timeline of the universe where nothingness existed. It seems to me that the claim that there was nothingness before the big bang would violate these laws. For example if E is the total energy of the universe then the law states that E = constant. If E1 is the total energy of the universe at an arbitrary time t1 and E2 is the total energy of the universe at arbitrary time t2 , then E1 = E2. let's say t1 is before the big bang and t2 is right now. If there was nothingness before the big bang, then E1 = 0. Since right now it is obvious that E2 > 0 , or , E2 != 0, then E1 != E2 which would violate conservation of energy. Is this line of reasoning correct? if not, why?
Why do you think it's obvious? It is not.
There is a possibility that E2=0. See Lawrence Krauss' book "A Universe from nothing", for example.
 
  • #7
How do we know that the big bang is the origin of time and not just an event that happened in time? Is there a mathematical/scientific reason or is it an axiom we have adopted?

If total universal energy is not conserved in GR , is it still conserved in isolated systems? Is it also true that universal E conservation does not apply to SR?

As for the current total E being 0... How is this possible? Wouldn't that mean nothing can happen?
 
  • #8
toothpaste666 said:
How do we know that the big bang is the origin of time and not just an event that happened in time? Is there a mathematical/scientific reason or is it an axiom we have adopted?
We don't know, we just have a model that represents reality incredibly well and as has already been stated, it is unable to handle what happened at or before the big bang singularity (aka t=0) or if there even IS a "before".

If total universal energy is not conserved in GR , is it still conserved in isolated systems? Is it also true that universal E conservation does not apply to SR?
Just today I made a post claiming that energy is conserved in closed systems and was told that that is wrong. See here:

https://www.physicsforums.com/threads/universe-already-existed.795055/#post-4993340
 
  • #9
  • #10
Ok thanks i have some stuff to read now. Btw sorry i didnt realize such a similar question had been posted. In fact i just realized how often you guys probably get this exact question. Sorry :( in school i am still studying classical physics so i have so far only been taught that total E is always conserved and have even done several experiments myself that demonstrated this, so the idea that the energy laws do not always hold is new to me
 
  • #11
Energy is conserved in special relativity, and there is still local energy conservation in general relativity (which means your lab experiment won't find a deviation).
 

1. What is the concept of "energy" before the big bang?

The concept of "energy" before the big bang is a topic of debate among scientists. Some theories suggest that the universe may have been in a state of pure potential or energy before the big bang, while others propose that the concept of energy may not have existed before the big bang.

2. Can we apply the laws of physics to understand the energy before the big bang?

Currently, our understanding of physics is limited to the post-big bang universe. As such, it is difficult to apply the laws of physics to explain the energy before the big bang. However, some theories, such as string theory, attempt to bridge this gap and provide insight into the pre-big bang universe.

3. Was there a source of energy that triggered the big bang?

This is a complex question that has not yet been definitively answered. Some theories propose that the big bang may have been triggered by a quantum fluctuation, while others suggest that it was a result of a collision between two universes.

4. How does the concept of energy fit into the theory of the big bang?

In the traditional big bang theory, the universe began as a singularity with infinite density and temperature. As the universe expanded, the energy became less dense and cooled down. This energy is responsible for the expansion and evolution of the universe.

5. Is it possible to measure or observe the energy before the big bang?

Currently, there is no way to directly measure or observe the energy before the big bang. However, scientists are constantly developing new technologies and theories that may provide insights into this elusive concept.

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