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Author Topic:   Does the universe have total net energy of zero?
Chuck77
Inactive Member


Message 31 of 404 (643730)
12-11-2011 4:19 AM
Reply to: Message 30 by Modulous
12-11-2011 3:38 AM


Re: pseudo tensors
It's beyond me. Can you simplify it some? What is negative energy compared to positive energy in the universe mean? Dark matter, dark energy etc?

Do some physicists say all the matter energy cancels eachother out therefore zero?

Edited by Chuck77, : No reason given.


This message is a reply to:
 Message 30 by Modulous, posted 12-11-2011 3:38 AM Modulous has responded

Replies to this message:
 Message 32 by Modulous, posted 12-11-2011 4:25 AM Chuck77 has responded

  
Modulous
Member (Idle past 1002 days)
Posts: 7789
From: Manchester, UK
Joined: 05-01-2005


Message 32 of 404 (643731)
12-11-2011 4:25 AM
Reply to: Message 31 by Chuck77
12-11-2011 4:19 AM


Re: pseudo tensors
It's beyond me. Can you simplify it some?

It's beyond me too, so no I can't.

What is negative energy compared to positive energy in the universe mean?

As far as I can tell negative energy is related to the gravitational field. Positive energy is energy as we generally use it.

Do some physicists say all the matter energy cancels eachother out therefore zero?

Not quite. They say the positive energy content of the universe is essentially cancelled out by the negative energy content of the universe.

Edited by Modulous, : No reason given.


This message is a reply to:
 Message 31 by Chuck77, posted 12-11-2011 4:19 AM Chuck77 has responded

Replies to this message:
 Message 33 by Chuck77, posted 12-11-2011 4:30 AM Modulous has responded

  
Chuck77
Inactive Member


Message 33 of 404 (643733)
12-11-2011 4:30 AM
Reply to: Message 32 by Modulous
12-11-2011 4:25 AM


Re: pseudo tensors
Modulous writes:

Not quite. They say the positive energy content of the universe is essentially cancelled out by the negative energy content of the universe.

Ok, but there is still energy right?

Im just not sure the theme is supposed to be, what the thread means. Zero energy or infinate energy, what means what?


This message is a reply to:
 Message 32 by Modulous, posted 12-11-2011 4:25 AM Modulous has responded

Replies to this message:
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PaulK
Member
Posts: 16860
Joined: 01-10-2003
Member Rating: 4.0


Message 34 of 404 (643735)
12-11-2011 4:48 AM


What I find most interesting
It seems to me that we have a consensus of experts, and so a rational ( but not logically valid, of course) reason to accept the idea that the total energy of our universe is near zero.

Against that we have:
Ignorance of the way that the value was calculated.
An inability to understand a paper (admittedly one that few - if any layman - could understand)
And the assertion that Dark Energy must upset the result - without even attempting to consider such basic matters as the magnitude of the difference.

Let us note that these arguments come from someone who considers himself knowledgable on logical fallacies and insists that a "good" argument from authority is logically valid!
The first two arguments are clearly not even remotely sensible, while the third could do with at least a basic investigation before being put forward as a serious objection.


  
Dr Adequate
Member
Posts: 16112
Joined: 07-20-2006


Message 35 of 404 (643736)
12-11-2011 5:06 AM
Reply to: Message 33 by Chuck77
12-11-2011 4:30 AM


Re: pseudo tensors
Ok, but there is still energy right?

But no net energy.

It's as though I gave you an IOU for a million dollars in exchange for your IOU for a million dollars. We'd then both have assets of a million dollars, which we have effectively created out of nothing, but we have no net assets, and no net wealth would have been created.

Edited by Dr Adequate, : No reason given.


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cavediver
Member (Idle past 2541 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

  
Trixie
Member (Idle past 2604 days)
Posts: 1011
From: Edinburgh
Joined: 01-03-2004


Message 37 of 404 (643738)
12-11-2011 5:54 AM
Reply to: Message 26 by designtheorist
12-11-2011 12:17 AM


Re: Is the total net energy in the universe zero?
I'm not in any way familiar with cosmology or physics (beyond the basics) so maybe I can explain to you why m can be disregarded.

If the total net energy in the universe is zero then, the positive energy content = the negative energy content so the equation can be written as,

mc2 = m Mu G / R u

Simplifying, we can cross out the m on either side of the equation. To illustrate, 2ab=4b, therefore simplifying gives 2a=4, a=2, Basic algebra tells you that whatever you do to one side of the equation you must do to the other. As jar would say, it really is that simple.

That's the point that is being made. Please bear in mind I'm not arguing one way or the other for a net energy of zero, I'm just explaining why basic algebra allows little m to be removed from both sides.


This message is a reply to:
 Message 26 by designtheorist, posted 12-11-2011 12:17 AM designtheorist has responded

Replies to this message:
 Message 42 by designtheorist, posted 12-11-2011 11:41 AM Trixie has responded

  
cavediver
Member (Idle past 2541 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

Replies to this message:
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Larni
Member
Posts: 3999
From: Liverpool
Joined: 09-16-2005


(1)
Message 39 of 404 (643741)
12-11-2011 6:58 AM


It can't be good when someone attempting to discuss these issues needs to have really basic algebra explained to them.

I'm reminded of when I was doing my A Levels at school (the last two years of high school, for you tax dodging colonials). When we wrote essays the idea was to be descriptive (rather than analytical).

It was an exercise in showing the teacher that you had put the work in and covered the body of knowledge appropriately.

As I did social sciences this boiled down to some variation of "Dr X suggests that 'X, Y and Z' is true, however Professor Q challenges this idea by saying 'A, B and C' is true".

That shows teacher you have done your work to learn (but not necessarily understand) the various conflicting theories.

I would suggest that all this quoting people saying 'X, Y and Z' and debating what was said (as opposed to debating the evidence) is indication of an absence of analysis going on, in a couple of threads recently.

This can be done without actually understanding subject to any great degree.

Kind of like the difference between A Level essays and post grad essays. This thread is a good example, I think, of this issue.


The above ontological example models the zero premise to BB theory. It does so by applying the relative uniformity assumption that the alleged zero event eventually ontologically progressed from the compressed alleged sub-microscopic chaos to bloom/expand into all of the present observable order, more than it models the Biblical record evidence for the existence of Jehovah, the maximal Biblical god designer.
-Attributed to Buzsaw Message 53

Moreover that view is a blatantly anti-relativistic one. I'm rather inclined to think that space being relative to time and time relative to location should make such a naive hankering to pin-point an ultimate origin of anything, an aspiration that is not even wrong.

Well, Larni, let's say I much better know what I don't want to say than how exactly say what I do.


  
cavediver
Member (Idle past 2541 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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designtheorist
Member (Idle past 2731 days)
Posts: 390
From: Irvine, CA, United States
Joined: 09-15-2011


Message 41 of 404 (643751)
12-11-2011 11:22 AM
Reply to: Message 30 by Modulous
12-11-2011 3:38 AM


Re: pseudo tensors
Anytime I am not persuaded because I don't understand something, I think the honest thing to do is to state what I don't understand. Perhaps someone can explain it to me and increase my understanding.

I also provided evidence to show why the portion I did understand indicates the author is wrong.


This message is a reply to:
 Message 30 by Modulous, posted 12-11-2011 3:38 AM Modulous has acknowledged this reply

  
designtheorist
Member (Idle past 2731 days)
Posts: 390
From: Irvine, CA, United States
Joined: 09-15-2011


Message 42 of 404 (643752)
12-11-2011 11:41 AM
Reply to: Message 37 by Trixie
12-11-2011 5:54 AM


Reply to Trixie - #37
What you have supplied is a circular argument. According to the author of the website:
(a) E (positive) = mc 2

and

(b) E (negative) = - m M u G / R u

The negative energy equation relates to gravity. So, as you point out, if the positive and negative are equal, then you can say:

mc 2 = m M u G / R u

But this is exactly what I deny.

Look at the effect this has on Einstein's equation. The author changes E = mc 2 into E = c 2. He is changing one side of the equation without changing the other. This damages the equation. The equation now says Energy = Velocity (the specific velocity of speed of light squared) - which is nonsense.

Edited by designtheorist, : Italicized the "if"

Edited by designtheorist, : Clarification

Edited by designtheorist, : No reason given.


This message is a reply to:
 Message 37 by Trixie, posted 12-11-2011 5:54 AM Trixie has responded

Replies to this message:
 Message 44 by PaulK, posted 12-11-2011 12:07 PM designtheorist has responded
 Message 56 by Trixie, posted 12-11-2011 1:46 PM designtheorist has responded

  
designtheorist
Member (Idle past 2731 days)
Posts: 390
From: Irvine, CA, United States
Joined: 09-15-2011


Message 43 of 404 (643753)
12-11-2011 12:00 PM


Gravity and Pseudotensors
This forum is about "Understanding through Discussion" so I appreciate the participation from everyone.

Earlier I mentioned the paper discussing pseudotensors was not persuasive to me. Based on the context, pseudotensors appeared to be some kind of modeling element but I did not know know what they represented. I stumbled across this article in Wikipedia which provides a decent definition.

See http://en.wikipedia.org/wiki/Gravitational_energy

This article contains one very interesting sentence:

Some people object to this derivation on the grounds that pseudotensors are inappropriate in general relativity, but the divergence of the combined matter plus gravitational energy pseudotensor is a tensor.

This seems to be a defense of the use of pseudotensors, but not a strong defense.

I am still looking for a paper that provides actual data used to estimate the total net energy. I have not found one. I am curious how Feynmann's calculation (which I am betting did use actual data) may have found net zero energy when dark energy was unknown and people still come up with net zero when we know the universe is 72% dark energy. It doesn't make sense.

Edited by designtheorist, : No reason given.


  
PaulK
Member
Posts: 16860
Joined: 01-10-2003
Member Rating: 4.0


Message 44 of 404 (643754)
12-11-2011 12:07 PM
Reply to: Message 42 by designtheorist
12-11-2011 11:41 AM


Re: Reply to Trixie - #37
quote:

The negative energy equation relates to gravity. So, as you point out, if the positive and negative are equal, then you can say:

mc 2 = m M u G / R u


But that is not what the website says. The website says simply that it will eliminate m from BOTH sides, which is changing both in the same way - and compare them. Since m must be greater than zero this is mathematically valid.

There is no circular argument here.


This message is a reply to:
 Message 42 by designtheorist, posted 12-11-2011 11:41 AM designtheorist has responded

Replies to this message:
 Message 45 by designtheorist, posted 12-11-2011 12:23 PM PaulK has responded

  
designtheorist
Member (Idle past 2731 days)
Posts: 390
From: Irvine, CA, United States
Joined: 09-15-2011


Message 45 of 404 (643755)
12-11-2011 12:23 PM
Reply to: Message 44 by PaulK
12-11-2011 12:07 PM


Reply to PaulK #44
There are several errors in the website argument. I don't think we need to go into all of them. Both Trixie and the website author are providing circular arguments.

Trixie uses the word "if." The word "if" is required. She is assuming the two equations are equal. i deny this.

The website author does not use the word "if" but he makes the same assumption when he writes:

We can eliminate m from both terms (since it is a hypothetical particle anyway) and compare:

(a) the value of c 2

with

(b) the value of - M u G / R u

Do you see how he is assuming they are equal?

The website author ends by saying

positive energy = 9 x 10 16
negative energy = - 9.77 x 10 16

Since this is only about 8% difference, he is saying the answer is probably zero. The problem is his calculation for positive energy is nothing but the speed of light squared - it is velocity.

So what does this do to Einstein's equation? The author is saying that Einstein is wrong. E does not equal mc 2. Instead, E = c 2.

C'mon. Seriously? Do we have to spend any more time on this?


This message is a reply to:
 Message 44 by PaulK, posted 12-11-2011 12:07 PM PaulK has responded

Replies to this message:
 Message 46 by PaulK, posted 12-11-2011 12:36 PM designtheorist has responded
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