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Author Topic:   Does the universe have total net energy of zero?
cavediver
Member (Idle past 2585 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(3)
Message 36 of 404 (643737)
12-11-2011 5:20 AM
Reply to: Message 25 by designtheorist
12-10-2011 11:49 PM


Re: Reply to Modulous
A quick reading of the paper did not convince me the author is correct. For one thing, I'm not sure what pseudo-tensors are or how they might be helpful in estimating total net energy.

where-as papers that use tensors instead of pseudo-tensors to talk about total energy are much more likely to be correct?

Someone is wrong here... Modesty would indicate it is probably me.

That's a great statement and I was going to give it a "thumbs up". Sadly, Im not really seeing much of that modesty here, just a whole heap of stupidity.

I'll be back later this morning with a full response.


This message is a reply to:
 Message 25 by designtheorist, posted 12-10-2011 11:49 PM designtheorist has not yet responded

  
cavediver
Member (Idle past 2585 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(1)
Message 38 of 404 (643739)
12-11-2011 6:55 AM
Reply to: Message 11 by designtheorist
12-10-2011 10:19 AM


Re: Is the total net energy in the universe zero?
I laughed out loud. I thought "Larry's lost it! No one is going to believe the net energy in the universe is zero or even close to zero!"

Yes, because when a theoretical physicist presents a concept from theoretical physics, the smart-money is on laughing off the concept as wrong. I mean, it's not as if theoretical physics is known for presenting concepts that seem to run slightly counter to common sense

And what do you mean by "close to zero"? What magnitude scale are you using to determine whether some supposed dimensional number is close to zero?

When can gravitational field energy be greater than the positive energy of the matter?

When we are looking at cosmological scale gravitation/curvature, and not just local gravitational effects. Gravity is non-linear. You don't get large scale effects by adding up all the small scale effects.

Second, there is nothing to offset the positive heat energy of the universe.

This is included in the mass content of the Universe. And furthermore is negligible compared to the rest-mass, so wouldn't be a problem even if it was excluded. But it's not.

If a gravitational field has negative energy, then dark energy must be positive energy.

In one way of looking at it, yes. But again, this is already included in the mass-energy of the Universe. Remember how it is always explained that the Universe is 5% matter, 23% dark matter, 72% dark energy - this is what accounts for the positive energy, and the curvature of the Universe accounts for the equal negative energy. How do we know this balances? Because the Universe appears to have flat spatial-section, and that's the clincher.


This message is a reply to:
 Message 11 by designtheorist, posted 12-10-2011 10:19 AM designtheorist has responded

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cavediver
Member (Idle past 2585 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(9)
Message 40 of 404 (643743)
12-11-2011 8:04 AM


Does any of this matter or even make sense?
Yes and no

I have often repeated that there is no good definition of energy in General Relativity. It is a concept that works well on the small-scale (so just about everything within our experience) but as you start to deal with large volumes of curved space-time, you realise that all the hard "facts" regarding conservation seem to soften, and sometimes vanish completely. When you then jump to talking of the energy of the whole Universe, you are then very close to making the classic category error, confusing the contents of the Universe with the Universe itself.

There are some ways of making semi-rigorous definitions of the total energy, and this is what we see discussed in the literature and made reference to in the colloquial presentations by Hawking, Krauss, etc.

The fact is, if we are being very colloquial, that General Relativity is almost the statement that the gravitational energy is always equivalent to the mass-energy. That is the very constraint that dictates what is and what is not allowed in space-time physics. So there is nothing surprising in any of this. Adding in dark energy, dark matter, etc makes absolutely no difference to this - GR is essentially balancing the gravitational energy against all the other inputs.

Why then all the fuss?

It simply comes down to being able to answer the moronic question of "so how do we get something from nothing?" If we can reply that the Universe is essentially nothing, then we can probably get the questioner to shut-up, as we know that there is no way in hell we're going to be able to explain the truth behind the nature of energy in space-time physics in a matter of minutes, hours, or even days.

The Universe as a quantum fluctuation is a great idea, but it is certainly not an answer to "something from nothing" - there is an arena in which this quantum fluctuation took place, whether that is pre-existing space or something more abstract. So it is inescapably something from something. So who cares whether the total energy of the Universe is zero? And in other cosmogenetic ideas, such as colliding branes, there is simply no requirement for the total energy to be zero.

The only alternative is what I've just decided to call "something not from anything" (which is actually what every possible answer will revert to once you look at it from the right scale. A Universe with infinite past is of this nature)

This is our classic Big-Bang inspired universe that has a finite past, and no greater space-time in which it is embedded. The singularity at T=0 marks the breakdown where GR cannot handle the topology change of the spatial sections closing round on themselves (think of "cylindrical" circles of latitude collapsing to a point at the Poles, turning the surface of the Earth from a cylinder into a sphere) We get hints of this being possible behaviour from Hawking's No-Boundary Proposal.

Who cares what the total energy of this universeis. It didn't "come" from anywhere. It is just an internal property of this isolated universe. Conservation of energy works well-enough when you are away from problematic areas such as T=0, but the concept breaks down completely as you approach that point.

So... my viewpoint on all of this is that it is a bit of a non-issue. Yes, it is quite possible to look at the Universe and see it as having zero total energy, and if our Universe started as a quantum fluctuation, this might actually be relevant. But rather than using this as an answer to "how do you get something from nothing", I would challenge the questioner to actually define what he means by "something" and "nothing" first - and when he fails, simply smile condescendingly

Edited by cavediver, : No reason given.


Replies to this message:
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 Message 65 by designtheorist, posted 12-11-2011 5:36 PM cavediver has responded

  
cavediver
Member (Idle past 2585 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(1)
Message 67 of 404 (643783)
12-11-2011 5:55 PM
Reply to: Message 65 by designtheorist
12-11-2011 5:36 PM


Re: Does any of this matter or even make sense?
colliding branes are not required by M theory and will never become the accepted view of how the universe started because observational support is impossible.

First, please do not abuse terminology in which you have no understanding. Secondly, are you under some bizarre impression that because we may never be able to understand precisely why the Universe is here owing to limitations in our observations, that this somehow implies the need for some type of creator being? i.e. "we may never be able to tell which of theoretical physics' ideas A, B, or C is correct, or indeed if any are correct... therefore GOD"

If the claim is that net total energy will always be zero no matter what new positive energy (such as dark energy) is discovered in the universe, then the theory is fatally flawed and explains nothing.

no, it simply means you haven't a clue about what I have just explained.


This message is a reply to:
 Message 65 by designtheorist, posted 12-11-2011 5:36 PM designtheorist has responded

Replies to this message:
 Message 73 by designtheorist, posted 12-11-2011 7:34 PM cavediver has responded

  
cavediver
Member (Idle past 2585 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(1)
Message 68 of 404 (643784)
12-11-2011 6:02 PM
Reply to: Message 59 by designtheorist
12-11-2011 2:15 PM


Re: A Simple Thought Experiment
Now when you convert this mass into positive energy, the gravitational field energy goes to zero.

Why on earth would this happen?


This message is a reply to:
 Message 59 by designtheorist, posted 12-11-2011 2:15 PM designtheorist has responded

Replies to this message:
 Message 71 by designtheorist, posted 12-11-2011 7:28 PM cavediver has responded

  
cavediver
Member (Idle past 2585 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(1)
Message 74 of 404 (643791)
12-11-2011 7:40 PM
Reply to: Message 71 by designtheorist
12-11-2011 7:28 PM


Re: A Simple Thought Experiment
Of course I was referring to the gravitational energy associated with the converted mass only - not all gravitational energy.

Yes, I realise that. So my question remains.

The point is that you are making declarations of what is correct or not, based on a rather poor and mainly incorrect understanding of physics. In this particular case, you seem to think that gravity couples to matter but not to the "energy" that is released when this matter is annihilated. This is incorrect.


This message is a reply to:
 Message 71 by designtheorist, posted 12-11-2011 7:28 PM designtheorist has responded

Replies to this message:
 Message 78 by designtheorist, posted 12-12-2011 12:51 AM cavediver has responded

  
cavediver
Member (Idle past 2585 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(2)
Message 82 of 404 (643809)
12-12-2011 2:09 AM
Reply to: Message 78 by designtheorist
12-12-2011 12:51 AM


Re: A Simple Thought Experiment
It is my understanding that massless particles are subject to gravitational attraction from other massive bodies but massive bodies (or massless particles) are not subject to attraction to massless particles. If you believe this is incorrect, please provide a reference or link.

I do not *believe* you to be incorrect - you simply *are* incorrect. You keep asking for references and papers that would back up the most basic understanding of General Relativity and cosmology. Might I suggest you gain this understanding first, and then perhaps you wouldn't look quite so foolish. Go buy a copy of Gravitation by Misner, Thorne, and Wheeler, and get back to us in a couple of years.

Edited by cavediver, : No reason given.


This message is a reply to:
 Message 78 by designtheorist, posted 12-12-2011 12:51 AM designtheorist has not yet responded

  
cavediver
Member (Idle past 2585 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(3)
Message 83 of 404 (643810)
12-12-2011 2:24 AM
Reply to: Message 73 by designtheorist
12-11-2011 7:34 PM


Re: Does any of this matter or even make sense?
I'm saying colliding branes is a theory which will never become accepted because cosmologists of all religious or anti-religious persuasions will never embrace a theory which is purely theological with no observational support.

Purely theological?

Really? Here is one of the original papers discussing this possibility. To be honest, it doesn't look too much like any of the theological papers I have read. And given that different types of colliding brane ideas give rise to differrences in the very early Universe which in turn lead to different signatures within the CMBR, then your "no observational support" is also wrong.

You are really not doing too well in this thread, are you?


This message is a reply to:
 Message 73 by designtheorist, posted 12-11-2011 7:34 PM designtheorist has responded

Replies to this message:
 Message 95 by designtheorist, posted 12-12-2011 3:19 PM cavediver has responded

  
cavediver
Member (Idle past 2585 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(8)
Message 102 of 404 (643891)
12-12-2011 3:44 PM
Reply to: Message 95 by designtheorist
12-12-2011 3:19 PM


Re: Does any of this matter or even make sense?
The impetus and motivation for the colliding branes theory is purely theological. Surely this is not the first time you have heard this criticism?

yes, it is. And it is ludicrous and imbecilic. And as I actually know the two authors of the paper I presented, I can assure that it is also utterly wrong; hilariously wrong

I disagree. And I'm not alone. Many physicists, including atheist physicists, see colliding branes as nothing but a notion arising from atheistic motivations.

Care to mention some of these supposed physicists? I can assure you, as one of the physicists who worked in this area, that you are talking complete bollocks. For the record, for all the time I worked as a theoretical physicist, I was a born-again evangelical Christian, attending various Vineyard fellowships around the world. So you would have perhaps thought that I would have been a little bit aware of these atheistic tendancies amongst my colleagues?

More importantly, the central thesis of the OP has stood up quite well.

No, it is as much nonsense as it was to begin with.

I've not seen any evidence contradicting the central point.

You have seen my explanation. You have not understood it. So you have dismissed it. So you remain as wrong as you were at the beginning. What more is there to say?


This message is a reply to:
 Message 95 by designtheorist, posted 12-12-2011 3:19 PM designtheorist has responded

Replies to this message:
 Message 108 by designtheorist, posted 12-12-2011 7:19 PM cavediver has not yet responded

  
cavediver
Member (Idle past 2585 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(1)
Message 120 of 404 (643928)
12-13-2011 2:53 AM
Reply to: Message 116 by designtheorist
12-13-2011 1:16 AM


Re: Hamiltonian definition of energy always equals net zero
You claim that you understand what I have been writing yet here I find you writing this:

While doing a little reading tonight, I learned that under certain definitions of energy the net total is always zero.

yet you managed to completely miss this in message 40:

cd writes:

The fact is, if we are being very colloquial, that General Relativity is almost the statement that the gravitational energy is always equivalent to the mass-energy. That is the very constraint that dictates what is and what is not allowed in space-time physics. So there is nothing surprising in any of this. Adding in dark energy, dark matter, etc makes absolutely no difference to this - GR is essentially balancing the gravitational energy against all the other inputs.

And then we have...

It seems how one defines energy has a lot to do with the result you get from calculations.

when 76 messages earlier I had written

CD writes:

I have often repeated that there is no good definition of energy in General Relativity....
...There are some ways of making semi-rigorous definitions of the total energy, and this is what we see discussed in the literature and made reference to in the colloquial presentations by Hawking, Krauss, etc.

It seems Professor John Baez does not think too highly of any definition which requires energy to net to zero.

Really? Or perhaps he just knows that " there is no good definition of energy in General Relativity..."

If it wasn't for weveryone else here, I'd wonder why I bother. Try not being so so very desperate to be right...


This message is a reply to:
 Message 116 by designtheorist, posted 12-13-2011 1:16 AM designtheorist has responded

Replies to this message:
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cavediver
Member (Idle past 2585 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(5)
Message 154 of 404 (644640)
12-19-2011 5:55 PM
Reply to: Message 153 by designtheorist
12-19-2011 2:52 PM


Re: Is net zero energy universe "not even wrong?"
A more heinous error in terminology is calling dark energy the "cosmological constant."

Listen, you half-witted arrogant twit, just about everything you write here is WRONG - ridiculously wrong. So try not to make such stupid statements as the above. Dark energy is correctly considered as possibly the result of a cosmological constant. You ask me to bring my A-game here - first I need silence from the annoying kid in the corner, so STFU and STFD.


This message is a reply to:
 Message 153 by designtheorist, posted 12-19-2011 2:52 PM designtheorist has responded

Replies to this message:
 Message 156 by designtheorist, posted 12-19-2011 6:14 PM cavediver has responded

  
cavediver
Member (Idle past 2585 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(2)
Message 155 of 404 (644642)
12-19-2011 6:04 PM
Reply to: Message 139 by designtheorist
12-17-2011 2:21 PM


Re: On the nature of negative gravitational energy – Part II
Can gravitation ever equal the rest energy of mass of the universe?

Gravitation is not energy so the question makes no sense.

Let’s say, for the sake of argument, that the gravitational field is negative.

The gravitation field is described by a tensor field, and so cannnot be simply "negative".

Gravitation is a secondary form of energy.

No, it is not.

That is, its existence is dependent on the existence of matter.

No, it most certainly is not. Consider any of the vacuum solutions of General Relativity.

How then can gravity have the same amount of energy as mass?

Gravity is not energy so the question makes no sense.

Can gravity release thermal energy in the same way a star can?

?????

Can gravity display kinetic energy the way galaxies and planets can?

?????

At the local level, gravity is one-billionth the power of the rest energy of mass as normal densities such as planets and luminescent stars.

Gravity is not a power and is not energy...

You really do need to realise just how little you understand here, and just how much pure gibberish you are spouting.


This message is a reply to:
 Message 139 by designtheorist, posted 12-17-2011 2:21 PM designtheorist has responded

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 Message 159 by designtheorist, posted 12-19-2011 6:27 PM cavediver has not yet responded

  
cavediver
Member (Idle past 2585 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(1)
Message 157 of 404 (644644)
12-19-2011 6:18 PM
Reply to: Message 137 by designtheorist
12-17-2011 2:18 PM


Re: On the nature of negative gravitational energy – Part I
Really, Dr. Guth? According to this thinking, the smallest particle would have the largest gravitational field.

How the hell did you conclude this???

Perhaps I am missing the point...

Ya think?

...but let’s examine this.

Yes, let's...

It appears that energy is extracted from the hollow shell of mass by reducing the size of the mass.

Ok...

If one reduces the mass...

Huh? Where the hell did you get that from? Can you really not spot the obvious mistake? Reducing the volume occupied by the mass is *NOT* reducing the mass. So we have learned how you managed to make such an stupid mistake above regarding your "smallest particle".

The fact the region of the field is increased is meaningless.

Nope - we've just established that your reading comprehension is non-existent. Which is not good, when you're trying to lecture professionals and educated informed amateurs. You just end up looking like an idiot.

Edited by cavediver, : No reason given.


This message is a reply to:
 Message 137 by designtheorist, posted 12-17-2011 2:18 PM designtheorist has responded

Replies to this message:
 Message 161 by designtheorist, posted 12-19-2011 6:37 PM cavediver has not yet responded

  
cavediver
Member (Idle past 2585 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(1)
Message 158 of 404 (644645)
12-19-2011 6:24 PM
Reply to: Message 156 by designtheorist
12-19-2011 6:14 PM


Re: Is net zero energy universe "not even wrong?"
Charming

I'll tell you what is not charming:

Really, Dr. Guth? According to this thinking, the smallest particle would have the largest gravitational field.

It is this smug arrogant bullshit, thinly veiling your chasm of ignorance, that makes me wretch. Pathetic.


This message is a reply to:
 Message 156 by designtheorist, posted 12-19-2011 6:14 PM designtheorist has responded

Replies to this message:
 Message 160 by designtheorist, posted 12-19-2011 6:29 PM cavediver has not yet responded

  
cavediver
Member (Idle past 2585 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(1)
Message 194 of 404 (644839)
12-21-2011 4:23 AM
Reply to: Message 193 by Dr Adequate
12-21-2011 3:53 AM


Re: A Simple Thought Experiment
designtheorist writes:

For one thing, it peeves me to see dark energy referred to as the Cosmological Constant. In Einstein's mind the lambda was all about maintaining a static state universe. Dark energy does not do that.

Dr Adequate writes:

* sighs *

The cosmological constant has different effects depending on its value...

...The cosmological constant is not defined by what Einstein wanted it to do, but by the role it plays in the equations of GR.

Thank you. The "peeves" comment had completely drained any enthusiasm whatsoever to continue replying to this nonsense. I'm glad that someone still has the stomach for it.

Edited by cavediver, : No reason given.


This message is a reply to:
 Message 193 by Dr Adequate, posted 12-21-2011 3:53 AM Dr Adequate has not yet responded

  
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