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Does vacuum energy rely on the existence of matter?

by diffusion
Tags: energy, existence, matter, rely, vacuum
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diffusion
#1
Aug23-07, 10:24 AM
P: 73
From what I understand, vacuum energy is a form of energy that exists in freespace, even when completely devoid of matter. So, I have two questions:

1. Can vacuum energy exist if there were no matter anywhere in the universe?

2. If so, where does this vacuum energy come from?
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marcus
#2
Aug23-07, 10:44 AM
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Quote Quote by diffusion View Post
From what I understand, vacuum energy is a form of energy that exists in freespace, even when completely devoid of matter. So, I have two questions:

1. Can vacuum energy exist if there were no matter anywhere in the universe?

2. If so, where does this vacuum energy come from?
what do you include in your idea of matter? are gravitons matter? are "Boltzmann brains", if they exist, matter? if space has a nonzero temperature does this require the existence of some sort of matter? I find it hard to imagine a universe without matter.

================

I guess one reason I find it hard to imagine a spacetime with "no matter anywhere" is that
spacetime is basically a network of relationships between events-----some version of matter seems to be required in order for there to be events
without matter, no events----without events, no spacetime

maybe someone else can see more clearly what you are talking about, and give a better answer
SpitfireAce
#3
Aug23-07, 11:11 AM
P: 137
well, vacuum energy is caused by the uncertainty fluctuation of an electromagnetic field, so I guess you're asking... if there were no charged particles, would the electromagnetic field still exist... well, I would say that the fact that vacuum energy exists in the first place gives the field a real existence, so I would imagine that it would still exist and fluctuations in it would still occur... unless of course the existence of the vacuum fluctuations relies on the em gauge symmetry being local (I don't see why it would) in which case they, like all other em phenomena, would cease

diffusion
#4
Aug23-07, 11:34 AM
P: 73
Does vacuum energy rely on the existence of matter?

Quote Quote by marcus View Post
what do you include in your idea of matter? are gravitons matter? are "Boltzmann brains", if they exist, matter? if space has a nonzero temperature does this require the existence of some sort of matter? I find it hard to imagine a universe without matter.

================

I guess one reason I find it hard to imagine a spacetime with "no matter anywhere" is that
spacetime is basically a network of relationships between events-----some version of matter seems to be required in order for there to be events
without matter, no events----without events, no spacetime

maybe someone else can see more clearly what you are talking about, and give a better answer
I know, its slightly confusing, but I was asked this question in an astronomy class and must write a paragraph on it. I suppose matter is defined as anything that has mass and is made of fundamental particles such as quarks. Let's say no matter ever existed anywhere in the first place, and suppose all that is left to make up the "universe" is a completely flat, empty spacetime with no mass or radiation of any kind: could vacuum energy exist then?
diffusion
#5
Aug23-07, 11:36 AM
P: 73
Quote Quote by SpitfireAce View Post
well, vacuum energy is caused by the uncertainty fluctuation of an electromagnetic field, so I guess you're asking... if there were no charged particles, would the electromagnetic field still exist...
I suppose this answers the question actually. No matter = no charged particles = no electromagnetic field = no vacuum energy, assuming charged particles or any other form of matter never existed in the first place.
SpitfireAce
#6
Aug23-07, 12:24 PM
P: 137
well, thats like saying that space-time doesn't exist without matter... I think it would, it would just be flat (non-local)... well, the electromagnetic field is the same... if there were no charged particles the electro-magnetic field would be flat and a have a value of 0... the reason that the vacuum energy exists in the first place is because the uncertainty principle prohibits you from knowing the position (field value) and momentum (energy) of the field... if the electro-magnetic field is flat and the energy is 0, you know both at any given point... thus the energy at any one point in the field never drops down to exactly 0, but fluctuates around... these fluctuations are "vacuum energy"... so the field, with or without charged particles, would fluctuate according to quantum mechanics... all the classical electromagnetic phenomena like light depend on there being charged particles (local field) and thus would not exist (just like gravity wouldn't exist without massive objects)... but vacuum energy doesn't depend on whether or not charged particles exist in the field, it only depends on the rules of quantum mechanics, which would still exist without matter... that's my reasoning... but this is pretty philosophical since our physics is based on a world with matter...
TR345
#7
Sep17-07, 09:10 PM
P: 121
I dont think that the source of the electromagnetic field phenomena is created by mass. Mass just enables an expression of the electromagnetic field that we can measure. Because all we detect is the expression of the magnetic field, we tend to confuse the expression with the field itself.
TR345
#8
Sep17-07, 09:24 PM
P: 121
Because the field has the ability to make expressions, it must contain that which is expressed.


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