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Pure energy?


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#1 gadget man

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Posted 10 May 2008 - 11:00 PM

Im a bit new to this and ive been asking this question to a few people but I havent had an answer yet. Can any one help?

Im asking if any one can give me a definition for pure energy? Does it even exist?

Thanks
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#2 Klaynos

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Posted 10 May 2008 - 11:12 PM

Energy is a property that things have/transfer.... So I'm going to say "pure" energy does not exist.
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#3 gadget man

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Posted 10 May 2008 - 11:25 PM

So if 'pure energy' doesnt exist could you tell me where all this energy thats around us came from?

also is there energy lying dormant around us that isnt being used or transfered? and how does the transformation take place?

I know this is alot of questions im quite annoying sometimes :P
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#4 YT2095

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Posted 11 May 2008 - 12:05 AM

in My opinion, an example of pure energy would be the Photon, or that created by antimatter annihilation.

the latter is certainly the most Effective method method known for the creation of pure energy, gram for gram.
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#5 timo

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Posted 11 May 2008 - 01:36 AM

in My opinion, an example of pure energy would be the Photon, or that created by antimatter annihilation.

Why would you think so other than that it spontaneously sounds like it makes sense? Example: If the photons created had momentum: Would they still be "pure energy"? If "yes, pure energy can have momentum": Why wouldn't they be pure momentum that can have energy? Why not pure photons that have both, energy and momentum?
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#6 YT2095

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Posted 11 May 2008 - 12:32 PM

I don`t understand what you`re asking?
is my answer wrong or something?
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#7 timo

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Posted 11 May 2008 - 12:43 PM

Yes, it is. As Klaynos said, energy is a property of some physical system i.e. something that describes the physical system/object. It is not a physical object by itself.
A photon is not "pure energy" similarly to a car not being "pure red". Even worse: If you agreed that all red cars are "pure red" (in which case the "pure" would be misleading as it does not carry any additional information) then only red cars were "pure red". Not all cars are red. But for example all elementary particles have energy. So if you called all particles that have some energy "pure energy" then all particles were "pure energy".
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#8 YT2095

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Posted 11 May 2008 - 01:04 PM

here: "As Dirac's theory shows, when matter and antimatter meet, they annihilate into pure energy"

bolded by Me, and taken from: http://www.particlep...itron-pair.html

so now I`m Really Confused :confused:
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#9 stevo247

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Posted 11 May 2008 - 01:28 PM

Is vacuum energy mass-free?
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#10 timo

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Posted 11 May 2008 - 03:20 PM

here: "As Dirac's theory shows, when matter and antimatter meet, they annihilate into pure energy"

bolded by Me, and taken from: http://www.particlep...itron-pair.html

- They do not call photon pairs produced in e+ e- annihilation "pure energy". What they supposedly mean by "pure energy" is some intermediate virtual particle with some energy and zero momentum (s-channel).
- Assuming with "pure energy" they meant the intermediate virtual particle I still do not like calling it "pure energy". I think it's wrong.

I think you are on the safe side if on the most fundamental level you take the stance of Klaynos seeing energy as a property of the physical object, not a physical object itself - or even worse: Something more fundamental than elementary physical objects. Yet, if you keep that in mind you can of course sensibly talk about energy being a physical object in an effective (=appropriate for the current topic) theory/framework. I find it perfectly appropriate to talk about "waste of energy" or "energy consumption" and stuff like that when it comes to technical stuff like power supply as long as you keep in mind what these terms really mean (conversion of a form of energy that you can use for your current application into a form that's useless to you).
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#11 swansont

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Posted 11 May 2008 - 03:47 PM

I think it's to differentiate the mass-energy from the photon energy in that blurb. Energy manifests itself in different forms, none of which a physicist is likely to call pure vs unpure. OTOH, photon energy is one form that is not associated with rest mass. It's purely the kinetic term of the energy equation.

Mostly semantics, IMO.
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#12 timo

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Posted 11 May 2008 - 04:20 PM

Well, if in the link YT gave with "pure energy" they really mean some s-channel particle then that's closer to mass (if you were to define mass as cms energy which is a reasonable definition) than to kinetic energy. So if you took that definition of "pure energy" and transferred it on the photon then the photon was kind of an anti-thesis of "pure energy".

I don't think the term "pure energy" has any use other than in "I think everything in fact consists of pure energy"-style crackpot ideas or "I don't want to bother with or explain the details here"-type of approaches/explanations.
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#13 Farsight

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Posted 11 May 2008 - 09:59 PM

Im a bit new to this and ive been asking this question to a few people but I havent had an answer yet. Can any one help?

Yes.

Im asking if any one can give me a definition for pure energy?

I can.

Does it even exist?

Definitely. Energy is the one thing that you cannot create or destroy. An electron has mass only because it has energy, by virtue of E=mc. If you destroy an electron by annihilating it with a positron, you destroy the mass and the charge, the the result is photons. They have energy.

However a photon is not pure energy. It's fairly close, but the motion and the polarization mean it doesn't quite fit the bill.

What does, is a black hole.

There is something else, something much more common, but people who don't understand this subject will accuse me of speculation or worse, so I'll leave it at that.
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#14 mooeypoo

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Posted 11 May 2008 - 10:09 PM

Definitely. Energy is the one thing that you cannot create or destroy. An electron has mass only because it has energy, by virtue of E=mc. If you destroy an electron by annihilating it with a positron, you destroy the mass and the charge, the the result is photons. They have energy.

Actually, you cannot create or destroy MATTER too, by the laws of thermodynamics. It's not the "only thing" that you cannot create or destroy.

What does, is a black hole.

There is something else, something much more common, but people who don't understand this subject will accuse me of speculation or worse, so I'll leave it at that.


I think I lost your point there, Farsight - are you saying a black hole is pure energy / made of only energy ?
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#15 ydoaPs

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Posted 11 May 2008 - 10:13 PM

What about charged BHs?
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#16 mooeypoo

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Posted 11 May 2008 - 10:30 PM

oookay, I was just firmly corrected by my more intelligent peers. Apparantly matter cannot be created or destroyed is a *classical* property.. whatever that means.

So, apparantly, matter and mass are dependantly perserved.. err.. Klaynos should explain this part, but my point is that I was wrong in that statement apparantly.

We learn somethin new every day. :)

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#17 Klaynos

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Posted 11 May 2008 - 10:30 PM

a black hole = pure energy? How the F does that work? If it is pure energy, then as suggested above it can have no other properties like well mass springs to mind... and bh's certainly have mass BUCKET LOADS of it...

And as discussed on IRC and mooey suggests just above, mass-energy is a conserved, NOT energy, and NOT mass, this is one of the interesting results of realtivity:

E2=p2c2 + (mc2)2
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#18 Farsight

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Posted 11 May 2008 - 11:24 PM

Let's not get confused about mass. Mass is invariant mass. An electron exhibits this property, a photon does not. Annihilation "destroys" mass. That invariant mass has gone.

Yourdadonapogos: charged black holes don't exist. Yes, we can see charge and dramatic magnetic flux whilst a black hole is swallowing matter, but once it's swallowed it, the charge has gone. Think about it. A black hole is black because light cannot escape it. A photon cannot escape a black hole. The photon is the "mediator" of electromagnetic force. If that can't escape a black hole, nor can electromagnetic force. This renders the Resner-Nordstrom concept invalid. The Kerr concept of a rotating black hole with angular momentum is also invalid, but I'd rather not go into it.

Klaynos: yes, black holes exhibit mass. When a black hole swallows a photon, its mass increases. But again it's only by virtue of E=mc. It's because mass and energy are merely two different ways of measuring energy. When you look at E=pc + (mc) and think about the electron prior to annihilation, imagine it's not moving, whereupon it has no momentum so E=(mc). After annihilation the electron has been converted into a 511KeV photon moving at c, and a photon has no mass but it does have energy/momentum E=hf or p=hf/c, so by conservation E=pc. Note that what we've basically got here is E = (mc) = pc, and that demonstrates the relationship between momentum and inertial mass. In essence momentum and inertia are the same thing. It depends on who you say is moving. The photon isn't quite pure energy because it's got a polarization and is moving at c. The black hole stops it. It acquires the photon energy/momentum and grows. Note that I say energy/momentum because they are two different measures of the same thing. One is distance based, the other is time based. That's why you divide by c (distance over time) to go from one to the other.

You'll have heard the saying "a black hole has no hair". It doesn't have much else either. That's why the black hole is pure energy.
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#19 Klaynos

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Posted 11 May 2008 - 11:29 PM

Mass-energy is also conserved in nuclear bonding, whereas neither mass nor energy are. So claiming that just energy cannot be created or destroyed is well wrong.

I still don't see how you can claim that black holes are pure energy? It makes no sense. They don't exhibit mass, they ARE massive, AND they have energy, they are NOT pure energy.

No I've never heard the saying "a black hole has no hair" it makes no sense. Black holes have ALOT of properties, some of which we don't really know about, but they sure as hell arn't pure energy....
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#20 iNow

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Posted 11 May 2008 - 11:40 PM

Klaynos,

I quite agree with your stance, just wanted to show you the origin of the "no hair" theorem, and what that ACTUALLY implies:


http://en.wikipedia....No_hair_theorem

The no-hair theorem in astrophysics postulates that all black hole solutions of the Einstein-Maxwell equations of gravitation and electromagnetism in general relativity can be completely characterized by only three externally observable classical parameters: mass, electric charge, and angular momentum. All other information about the matter which formed a black hole or is falling into it, "disappears" behind the black-hole event horizon and is therefore permanently inaccessible to external observers (see also the black hole information paradox).

This theory gets its name from a comment by the famous astrophysicist John Wheeler, who stated that “Black holes have no hair.” [1] Magnetic charge, if detected as predicted by some theories, would form the fourth parameter possessed by a classical black hole.

Example
For example, if two black holes are "constructed" so that they have the same masses, electrical charges, and angular momenta, but the first black hole is made out of ordinary matter whereas the second is made out of antimatter, they will be completely indistinguishable to an observer outside the event horizon. None of the special particle physics pseudo-charges (baryonic, leptonic, etc.) are conserved in the black hole.


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