Is the total energy of the Universe Zero?

AI Thread Summary
The discussion centers on whether the total energy of the universe is zero, with participants exploring the concept that equal amounts of positive and negative energy can theoretically cancel each other out. One contributor argues that every effect must have a cause, suggesting that existence cannot arise from non-existence, and posits that there must be an eternal cause behind the universe. Others clarify that while the idea of energy summing to zero is plausible, the definition of "nothing" is complex, involving the absence of matter and spacetime. They emphasize that from this "nothing," it is theoretically possible to derive matter and spacetime without contradicting physical laws. The conversation highlights the intricate relationship between energy, matter, and the origins of the universe.
LaserMind
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Excuse this beginners question, but someone asked me if the Universe can appear out of nothing. I answered yes, because all the energy in the Universe cancels out to make nothing. So, conversely, out of nothing can come equal positive and negative energy. He seemed half convinced.
Am I correct in what I said? Thanks for any replies.
 
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Nice topic..

We agree that Five minus Five = zero but in noway 0 is the cause of 5.
Ex: Add / multiply 0 to itself any no of times etc.its still 0.

There must be a cause for every effect. May be that cause is too subtle to be grasped by human mind. If world is effect, then it is a creation..I mean,there must be something which is eternal and that is what created this world. Existence can not come out of non-existence. This may sound like blind faith but on close observation it's logically correct.Do we not see this phenomenon everywhere in this world.
i.e, Every effect has a cause. In fact cause is the effect itself but in a finer form.

Ex:I think of an idea (be it any). When time and space are convenient, that thought will manifest in action. Isn't that how all discoveries made? So THOUGHT (cause) is the ACTION (effect) itself ..may be I can say 'cause' is 'effect' only in a pre-mature stage. So there is a cause for this world as well.
 
IamWhatIam said:
Nice topic..

We agree that Five minus Five = zero but in noway 0 is the cause of 5.
Ex: Add / multiply 0 to itself any no of times etc.its still 0.

There must be a cause for every effect. May be that cause is too subtle to be grasped by human mind. If world is effect, then it is a creation..I mean,there must be something which is eternal and that is what created this world. Existence can not come out of non-existence. This may sound like blind faith but on close observation it's logically correct.Do we not see this phenomenon everywhere in this world.
i.e, Every effect has a cause. In fact cause is the effect itself but in a finer form.

Ex:I think of an idea (be it any). When time and space are convenient, that thought will manifest in action. Isn't that how all discoveries made? So THOUGHT (cause) is the ACTION (effect) itself ..may be I can say 'cause' is 'effect' only in a pre-mature stage. So there is a cause for this world as well.

There is nothing wrong with equal amounts of positive and negative coming from nothing - mathematically they sum to zero (something analagous to waves cancelling each other out). OK, so what made a Universe appear at all, is at present also up for discussion, but I am not asking that.

My question is purely technical - is the sum total energy (or matter) in the Universe zero? I assume it would have to be zero?
Please correct me cosmologists out there.
 
I believe that Alan Guth pointed this out. A rocket traveling into orbit uses thrust to overcome the gravity of the Earth’s mass. So in a way, the effect of the thrust is positive energy and the effect of gravity is negative energy. Energy and matter are the same according to Einstein, and they both have mass. Gravity is a property of mass. So if you could add up all the matter and energy in the universe and then the respective gravity (negative energy) of that matter and energy, the result should be a net energy of zero.
 
LaserMind said:
Excuse this beginners question, but someone asked me if the Universe can appear out of nothing. I answered yes, because all the energy in the Universe cancels out to make nothing. So, conversely, out of nothing can come equal positive and negative energy. He seemed half convinced.
Am I correct in what I said? Thanks for any replies.

Yes, it is roughly correct, though different "nothings" can be defined and that simply speaking about energy without many added technicalities is not correct. In this case, "nothing" should be interpreted as "no matter, and no spacetime", which is a quite hard "nothing" indeed but still different from "nothing at all". From no matter and no spacetime it is possible to derive matter and spacetime, and from matter and spacetime it is possible to derive more matter, and more spacetime, without violating the laws of physics.
 
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It's a possibility. See
http://www.astrosociety.org/pubs/mercury/31_02/nothing.html
 
https://en.wikipedia.org/wiki/Recombination_(cosmology) Was a matter density right after the decoupling low enough to consider the vacuum as the actual vacuum, and not the medium through which the light propagates with the speed lower than ##({\epsilon_0\mu_0})^{-1/2}##? I'm asking this in context of the calculation of the observable universe radius, where the time integral of the inverse of the scale factor is multiplied by the constant speed of light ##c##.
The formal paper is here. The Rutgers University news has published a story about an image being closely examined at their New Brunswick campus. Here is an excerpt: Computer modeling of the gravitational lens by Keeton and Eid showed that the four visible foreground galaxies causing the gravitational bending couldn’t explain the details of the five-image pattern. Only with the addition of a large, invisible mass, in this case, a dark matter halo, could the model match the observations...
Hi, I’m pretty new to cosmology and I’m trying to get my head around the Big Bang and the potential infinite extent of the universe as a whole. There’s lots of misleading info out there but this forum and a few others have helped me and I just wanted to check I have the right idea. The Big Bang was the creation of space and time. At this instant t=0 space was infinite in size but the scale factor was zero. I’m picturing it (hopefully correctly) like an excel spreadsheet with infinite...

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