Talk:Negative energy

Hawking radiation

I intend to link the words 'negative energy' on the Hawking Radiation page to this page, and continue to develop the page. Arlington row (talk) 16:05, 5 October 2014 (UTC)

Negative electromagnetic energy?

Gravitational energy is negative. But gravitation is not the only attractive force with an inverse square law: it shares these properties with the electrostatic and magnetic attractions of particles with opposite polarities. Does this mean that the associated electromagnetic energy (which I gather is some weird form of "polarized" photons) is, like gravitational energy, negative? I have seen speculation in various places but no definitive reply from Someone Who Should Know. — Cheers, Steelpillow (Talk) 14:25, 19 August 2015 (UTC)

Comment

Hi, i hold a master in nuclear and particle physics, but do not at all consider myself an expert in these matters. That being said, i find this article very confusing at best. There is really nothing of value to find at the moment, except references to subjects it relates to. I'm sorry I don't have the expertise nor time to help improve this. A good understanding of Einsteins cosmological constant could help somewhat. Also energy isn't conserved on a general relativity scale (unless you change the definition of energy to make it fit, which is done at times to make explaining it more approachable). An understanding of inflation theory would help aswell to get to grips with this subject. — Preceding unsigned comment added by 195.244.164.245 (talk) 14:16, 2 June 2016 (UTC)

speculative?

Shouldn't the entire subject be listed as speculative (or at its most concrete, a semantic diversion)? Wikibearwithme (talk) 07:59, 2 September 2015 (UTC)

Not if the cited sources are to be respected, no. — Cheers, Steelpillow (Talk) 11:37, 14 September 2015 (UTC)

Gravity is also entirely speculative (you can't see it with your eyes, hold it in your hand) but we wouldn't say that in that article either because it fits the known facts. SpinningSpark 19:42, 14 September 2015 (UTC)

At least in classical physics there is no such definition of energy which would allow absolute value of energy. Therefore speaking about negative or positive energy is ill-founded, with all respect to Alan Guth, Stephen Hawking and their predecessors, like Edward Tryon and Richard C. Tolman mentioned in Zero-energy universe. The only thing which we can speak of is the difference of energy between two states. E.g. gravitational energy at the Earth's surface is lower then the one in infinity. We can postulate energy in infinity to be zero - but this is only a postulate made for convenience. It is consequence of nothing. Then energy at the Earth's surface is lower and hence negative - but only relatively to the gravitational energy in infinity. This simply means, that the energy of a stone on Earth is lower than in infinity. No one can say what is the gravitational energy of the stone in infinity. Unless one calculates total energy of the universe consisting only from the Earth and a stone in infinity, we cannot tell that stone in infinity has zero gravitational energy. Therefore "negative energy" and "zero-energy Universe" are only speculations. But, of course, my thoughts may also be wrong. Tachto (talk) 18:51, 3 February 2018 (UTC)

Fortunately, WP:RS saves us the need to speculate on what is or is not speculation. — Cheers, Steelpillow (Talk) 20:04, 3 February 2018 (UTC)

Increasing force does not imply increasing energy

I am no expert in this matter, but I have my doubts concerning the phrase: "At the same time the gravitational attraction - and hence energy - also increase in magnitude"

Force is not the same as energy (Energy is the integral over the distance of the force). So it is perfectly possible for the force to increase, while the energy decreases.

When two objects move towards another the gravitational force increases, but their potential energy due to the gravity decreases, while their kinetic energy increases (exactly according to the first law of thermodynamics).

Or did I make a mistake ? Feedback appreciated — Preceding unsigned comment added by Brigitte Van Gerven (talk • contribs) 09:16, 31 March 2016 (UTC)

It would be more correct the other way round, "At the same time the gravitational energy - and hence attraction - also increase in magnitude."

When one states that something negative is "decreasing" it is important to make clear whether one means "getting even more negative" or "decreasing in magnitude" because these are opposites. I find your remaining comments ambiguous in this respect. — Cheers, Steelpillow (Talk) 10:05, 31 March 2016 (UTC)

Yes, you made a mistake. It is the work done that is the integral of force over distance. Energy is the potential to do work and can be stored without anything moving anywhere. In this case we are speaking of the energy stored in the gravitational field. SpinningSpark 12:24, 31 March 2016 (UTC)

One can perhaps regard potential energy as the potential to do work, though it can also potentially do other things. It is certainly not customary to regard say a photon, a particle of pure energy, as being merely a potential to do work. — Cheers, Steelpillow (Talk) 15:36, 31 March 2016 (UTC)

How do you suppose a light sail works? SpinningSpark 16:06, 31 March 2016 (UTC)

You might like to consider why I included the word "merely" in my remark. — Cheers, Steelpillow (Talk) 17:32, 31 March 2016 (UTC)

Gravitational energy - Fate of the universe -

Hello, i am an architect and an engineer and also an amateur astronomer and i am not an expert what so ever on the topic, i am just interested in physics and cosmology. I write because I've found this section confusing and contradicting other related topics on wikipedia (linked further on) and not only. This is a proposal to change the text of a sentence in the chapter on gravitational energy https://en.wikipedia.org/wiki/Negative_energy I would like to propose a correction of the sentence : “ A universe in which positive energy dominates will eventually collapse in a "big crunch", while an "open" universe in which negative energy dominates will either expand indefinitely or eventually disintegrate in a "big rip"“ because I think that there is a mismatch of notions that contradict the causation of positive and negative energy, and it is also in contradiction with other related wikipedia articles (see in links). A. Positive cosmological constant corresponds to positive energy density which causes negative pressure (causes gravitational repulsion). B. Negative cosmological constant corresponds to negative energy density which causes positive pressure (causes gravitational attraction). (*1 Defined positive and negative energy from Etotal=Ekinetic+Epotential , where Ekinetic >0 (is positive (+)) and Egravitational potential <0 (is negative (-)) → Etotal= ½mv2 – GMm/r Note: Egravitational is defined correctly in the chapter as negative. (*2 If A=Emotion and B=Egrav then if B/A>1 → collapsion and when B/A<1 → expansion. density parameter Ω=B/A Substituting B/A for Ω then we get if Ω>1 we have a closed universe, Ω<1 we have an open universe and if Ω=1 (B=A) we get a flat universe (Energies cancel each other). (*1 Gravitational Potential Energy https://en.wikipedia.org/wiki/Gravitational_energy (*2 Lawrence Krauss Lectures „Something from Nothing“ I therefore propose that the sentence be as follows : “A universe in which negative energy dominates will eventually collapse in a "big crunch", while an "open" universe in which positive energy dominates will either expand indefinitely or eventually disintegrate in a "big rip"” links: http://www.preposterousuniverse.com/blog/2013/11/16/why-does-dark-energy-make-the-universe-accelerate/ „The negative pressure associated with dark energy is so large that it overcomes the positive (attractive) impulse of the energy itself, so the net effect is a push rather than a pull. The data say the dark energy density is positive, so a negative pressure is just the trick.”

https://ned.ipac.caltech.edu/level5/Carroll2/Carroll2_2.html

“a positive cosmological constant accelerates the universal expansion, while a negative cosmological constant and/or ordinary matter tend to decelerate it. “ https://en.wikipedia.org/wiki/Cosmological_constant “A positive vacuum energy density resulting from a cosmological constant implies a negative pressure, and vice versa. If the energy density is positive, the associated negative pressure will drive an accelerated expansion of the universe, as observed.” https://en.wikipedia.org/wiki/Ultimate_fate_of_the_universe “In a closed universe, gravity eventually stops the expansion of the universe, after which it starts to contract until all matter in the universe collapses to a point, a final singularity termed the "Big Crunch", the opposite of the Big Bang. “ “Even without dark energy, a negatively curved universe expands forever, with gravity negligibly slowing the rate of expansion. With dark energy, the expansion not only continues but accelerates. The ultimate fate of an open universe is either universal heat death, the "Big Freeze", or the "Big Rip",where the acceleration caused by dark energy eventually becomes so strong that it completely overwhelms the effects of the gravitational, electromagnetic and strong binding forces “ “Conversely, a negative cosmological constant, which would correspond to a negative energy density and positive pressure, would cause even an open universe to re-collapse to a big crunch. This option has been ruled out by observations.” “In the special case of phantom dark energy, which has even more negative pressure than a simple cosmological constant, the density of dark energy increases with time, causing the rate of acceleration to increase, leading to a steady increase in the Hubble constant.” https://en.wikipedia.org/wiki/Phantom_energy “Phantom energy is a hypothetical form of dark energy satisfying the equation of state with w < − 1 . It possesses negative kinetic energy, and predicts expansion of the universe in excess of that predicted by a cosmological constant, which leads to a Big Rip.“ more on Phantom energy: arxiv.org/abs/astro-ph/0703739v2 arxiv.org/abs/1402.4522v2

Thank you for considering all of this

My Best Regards PapAngelos (talk) 15:08, 2 August 2018 (UTC)

Proposed removal of portions of article discussing speculative non-scientific theories wormholes, time travel, and warp drives.

The concept of negative energy is complex enough that we don't need to muddy the waters with speculative non-scientific theories wormholes, time travel, and warp drives. Thoughts pro or con for excising the speculation? J Mark Morris (talk) 16:55, 27 January 2019 (UTC)

The criticism as "non-scientific" is not accurate. This kind of speculative physics is widely discussed in reliable sources, as evidenced in the main articles for these topics. A good many reputable scientists have studied them and/or written popular accounts. For example when a physicist of the calibre of Stephen Hawking writes on "How to build a time machine", there is nothing unscientific about it - just highly speculative. So it is not as if Wikipedia editors or a few fringe pseudoscientists are doing the speculating. As such, I think it essential that this article link to these topics and provide some basic context for the links. Offhand, I cannot think of a better way than the current dedicated section, so I think it should be kept. (I agree that time travel does not deserve a subsection, as it is a secondary effect of wormhole theory. But then it doesn't have one anyway, so there is nothing to excise on that score.) — Cheers, Steelpillow (Talk) 17:47, 27 January 2019 (UTC)

By non-scientific, I mean does not follow the empirical scientific method and is non-falsifiable. Perhaps I should have said that. Reputable scientists can have extremely active imaginations, as seen, in my opinion, these concepts as well as MWI and others. Unless more supporting comments appear, I will withdraw my request, since we don't have consensus. Thanks for replying! J Mark Morris (talk) 17:54, 27 January 2019 (UTC)

I find the article quite messy too, but in theoretical cosmology, speculation is the basic rule. For example, nobody ever measured the distance surrounding a spherical object using a Schwarzschild metric.Klinfran (talk) 20:46, 6 November 2022 (UTC)

Sorry.

field energy

There is no gravitational field energy, there is only a potential field and any object in the field has negative potential energy. The object needs the binding energy in order to escape and not the field. Ra-raisch (talk) 12:48, 18 June 2021 (UTC)

WhAt is ThaT arTiClE?

The gravitational energy section is completely wrong and uses some really ill defined vocabulary. This article, and the discussions in that page are really astounding. The potential energy IS NOT negative by definition since it is defined up to a constant. The constant is USUALLY taken such that the potential energy at infinity is 0, but it could be taken positive so that for any distance greater than a given radius the potential energy is positive. This is of no importance in classical physics since what is important is the DIFFERENCE in potential energy. And contrarily to what I read above from self proclaimed experts, the energy density of the gravitational field is positive, even in GR, it's a fairly recent certainty.Klinfran (talk) 20:41, 6 November 2022 (UTC)

recent developments

Recently, a collection of scientists and industry practitioners performed an experiment which seems to suggest ER = EPR, meaning quantum entanglement and quantum gravity are the same. This seems to contradict statements made by Roger Penrose about Wormholes in 2005 (see the wiki article) Ref: https://www.youtube.com/watch?v=uOJCS1W1uzg&t=1s — Preceding unsigned comment added by 167.98.254.244 (talk) 15:33, 5 December 2022 (UTC)

According to this report in Nature, the experiment aimed only to simulate a theoretical wormhole model. That is not an existential identity. — Cheers, Steelpillow (Talk) 09:51, 21 June 2023 (UTC)

dynamic Casimir effect as negative energy source

I see no mention here of the dynamic Casimir effect that can be used to produce more negative energy than the normal Casimir effect in theory. If one uses an optical resonator based on two close but not exact same frequency lasers aimed at a first mirror to cancel one another out but since frequencies are just not exactly the same there is a shift on shift off effect one could fastly switch a first holographic mirror that in turn switches around a secondary holographic mirror fast enough to lengthen and shorten a laser cavity in order to achieve the maximum dynamic casir effect. Since the frequency of a holographic mirror must be higher than tye frequency of the switched medium one would end up with either partially switching on and off parts of the main mirror in the laser cavity lengthening and shortening it to make it have this effect but one could also use multiple lasers towards a reflective surface switching it on and off. Please include the dynamic Casimir effect in the negative energy page and perhaps someone could calculate total negative energy yield or at least describe in the right terms why the dynamic Casimir effect if used at full potential delivers way more energy than the normal Casimir effect. — Preceding unsigned comment added by 84.24.84.243 (talk) 07:23, 16 March 2023 (UTC)

We would need a reliable source explicitly discussing the increase in negative energy, otherwise it would be original research on our part , which is not allowed. Note that fringe papers on wacky space drives are seldom reliable. — Cheers, Steelpillow (Talk) 09:44, 21 June 2023 (UTC)

Against proposal to delete WP:PROD

This article has been proposed to be deleted and then the mark WP:PROD was removed.

I have verified that Penrose does indeed claim that "negative energy" is a thing:

"In fact, negative energies can occur for real particles inside the black hole."

• Roger Penrose; The Road to Reality, ppbk, Vintage, 2005. Chapter 30: Gravity's Role in Quantum State Reduction.

The article is lame but the concept is valid. I oppose the proposal. Johnjbarton (talk) 15:41, 10 June 2023 (UTC)

Agreed. Use of the term in modern physics is well enough cited. Whatever it may be that this usage refers to, that needs to be covered here. — Cheers, Steelpillow (Talk) 09:36, 21 June 2023 (UTC)

The strange thing about this article is that it has no proper introduction and no definition of what we mean by "negative energy", and thus it is not clear what should be included in this article. Should we consider all cases where negative energy (relative to some 'free' state) can arise (e.g. evanescent waves, bound states, and spontaneous symmetry breaking could be argued to fit the bill), or is it only about a specific gravitational case and its relation to quantum field theory?

Currently it seems the selection of topics is largely based on Ford & Roman; "Negative energy, wormholes and warp drive". This is not ideal, as an encyclopedia article should not be based on a single article. Jähmefyysikko (talk) 13:16, 21 June 2023 (UTC)

I agree that an introductory section would help greatly. But we cannot, for example, say what it "is" unless and until we find a reliable source saying what it "is". The lede sentence says about all that can be said until then. Do you know of anything better? — Cheers, Steelpillow (Talk) 14:09, 21 June 2023 (UTC)

ergosphere

Does the existence of the ergosphere around a black hole have experimental support, or is it just a suggestion/hypothesis? — Cheers, Steelpillow (Talk) 09:33, 21 June 2023 (UTC)