Talk:Graviton
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How does it escape a black hole?
[edit]Does it travel faster than light? Nothing traveling under the speed of light can escape a black hole and if it doesn't leave a black hole the hole will not attract other objects. —Preceding unsigned comment added by 154.20.199.45 (talk) 01:53, 9 April 2010 (UTC)
- Planting a flag here on ideas for the hypothetical graviton and a different narrative consistent with experimental observation. Imagine that there are two fundamental particles, the electrino and positrino, which are -/+ 1/3 charge. Black holes are like compost piles - the more matter and energy added, the hotter the core gets, until it ignites and the ingested matter-energy is decomposed into electrinos and positrinos and form a plasma. An electrino/positrino pair in the plasma could be called a graviton. Gravitons are emitted/jetted via the polar jets of sufficiently energetic SMBH. The gravitons in the plasma can decay in energy and at sufficiently low energy they can emerge from the plasma as standard matter particles. For example, a free graviton (electrino/positrino pair) is a neutrino. An electron is a triplet of electrinos. A positron is a triplet of positrinos. It's easy to reverse engineer the standard model chart. This is a new hypothetical narrative, so I am only planting a flag here, not suggesting article changes at this time. J Mark Morris (talk) 18:15, 30 December 2018 (UTC)
- This is a dead comment for certain but I would like to clarify for future readers: the graviton is massless and therefore doesn’t experience any gravitational force. A theory of quantum gravity will be needed to explain how it escapes the screwed-up spacetime behind the event horizon, but the graviton has no issue escaping a gravitational field. OverzealousAutocorrect (talk) 18:42, 13 February 2024 (UTC)
- This is not correct explanation. Photon too is massless but it experiences gravitation due to having energy and cannot therefore escape black hole. IlkkaP (talk) 06:50, 24 August 2024 (UTC)
- In the context of Einsteinian gravity it doesn't actually even matter if it has any energy, because even straight lines are curved by gravity according to the geodesic equation, but in the Newtonian case where gravity is a force it still relates only the rest masses of particles (hence why relativistic particles or objects don't have much higher gravitational mass; observed gravitational mass should not depend on reference frame). Photons can't escape black holes because time stops at the event horizon; it is impossible to observe any object fully cross the event horizon in a finite period of coordinate time (although it can be done in finite proper time; see MTW Gravitation), let alone escape from it after entering.
- Either way, the OP is asking about quantum gravity which is not well understood at this time anyway. OverzealousAutocorrect (talk) 13:26, 24 August 2024 (UTC)
- Still wrong. Neither gravitons nor photons can escape black hole (and if they could, one could send information from inside black hole to outside). However, this doesn’t exclude black holes having gravitational and electric fields around them (i.e. black holes have mass and electric charge). IlkkaP (talk) 18:15, 24 August 2024 (UTC)
- We actually agree; I said in the comment you replied to that photons can't escape. All objects experience gravitation because gravitation is not a force but curvature of spacetime, and explaining why/how the graviton field works will require actually coming up with an accurate theory of quantum gravity, which we don't have. We also don't know that black holes can have electric fields; we have metrics that describe such black holes at the relativistic level, but whether or not the electromagnetic field behaves the same way at the quantum level is unknown because we've never directly measured the properties of a black hole at the quantum level. OverzealousAutocorrect (talk) 18:57, 25 August 2024 (UTC)
- Still wrong. Neither gravitons nor photons can escape black hole (and if they could, one could send information from inside black hole to outside). However, this doesn’t exclude black holes having gravitational and electric fields around them (i.e. black holes have mass and electric charge). IlkkaP (talk) 18:15, 24 August 2024 (UTC)
- This is not correct explanation. Photon too is massless but it experiences gravitation due to having energy and cannot therefore escape black hole. IlkkaP (talk) 06:50, 24 August 2024 (UTC)
- @IlkkaP @J Mark Morris @OverzealousAutocorrect Please limit your discussion to corrections or improvements in the article. See Wikipedia:Talk page guidelines. Wikipedia is not a forum. Try Physics StackExchange or Quora. Johnjbarton (talk) 19:08, 25 August 2024 (UTC)
Last section / difficulties
[edit]The description of the last section is redundant. It talks about gravity being non renormalisable, but in a language that ignores the notion of effective field theory. It is not a problem per se for a theory to be non-renormalisable. Once you have done a few measurements you can even _use_ this EFT. For instance the Fermi theory, you need to measure the four fermion interaction and then you can use this EFT to some higher energy scale. Same for gravity. This should be written more clearly. Pitorki (talk) 07:38, 8 October 2023 (UTC)
Too difficult? Are there sources which give simpler explanations?
[edit]@Schwabeditor you added a tag to the article claiming it was too technical. Obviously the article is not too mathematical. What is it that you think is too technical? Do you know of source which give simpler explanations? How can we improve and remove the tag? Johnjbarton (talk) 16:02, 14 February 2024 (UTC)
- I think that the concept of “graviton” is already highly technical. Just like articles on advanced Ricci calculus shouldn’t require too-technical tags because they are, by definition, very technical, this article shouldn’t either.
- If a plain-English definition must be given, simply say that the graviton is to gravity as the photon is to electromagnetism. Unfortunately it doesn’t get much simpler than that. OverzealousAutocorrect (talk) 18:15, 14 February 2024 (UTC)
Gravitons in speculative theories
[edit]I deleted a subsection of history named "Gravitons in speculative theories". Gravitons are speculative already. These works were not in any way "history". Only one could be considered possibility notable by citation count but there are many many "theories" of gravitation. Picking any without using a review reference is not fair. Johnjbarton (talk) 15:55, 7 April 2024 (UTC)
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