Talk:Relativistic jet

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[edit] Copyright infringement

Image:Galaxies_AGN_Inner-Structure-of.jpg

Does not have permission of authors of original scientific article to be published here.

Please delete.

Mr Brak 19:12, 13 April 2006 (UTC)

You originally uploaded this image and as creator released it (licensed it) under the GFDL. Are you now wishing to retract this? -- Curps 04:31, 14 April 2006 (UTC)

Yes. It was originally published in a paper with numerous authors. I don't have permission of the other authors to use it here. I didn't realize this was an issue when I originally uploaded it.

Mr Brak 02:20, 16 April 2006 (UTC)

At the moment this article is really just a diagram. I am planning on adding more text and explanations of this diagram soon.

[edit] Layman copy needed

"Collimates" isn't a common word. It wasn't in my vocabulary, at least. Could we have a better explanation for the layman? What exactly makes matter shoot out in these jets, in language I will understand? —RadRafe 13:49, 2 Apr 2005 (UTC)

Plasma physics - electrical universe - cosmology - doesn't believe in black holes and has different explanations for the jets. They start with wondering why a black hole which is supposed to be sucking everything in sight is expelling massive jets of plasma and radiation. I am just starting to study this so I am not competent to explain why they think all of the active nuclei galaxies can be explained as electrical effects - powerful electrical structures explain the features without the need of mythical black holes which only have validity in certain mathematical computations. This appears to me to be a more interesting avenue of exploration.

What? Who says black holes are mythical? By our understanding of the fundamental forces, whenever the gravity that a very massive object exerts on itself ceases to be countered by internal pressure, it is compressed to something smaller than its own Schwarzschild radius. That's a black hole. For black holes to not exist, there must be another pressure effect which kicks in after thermal pressure, radiation pressure, and electron and neutron degeneracy pressure have all failed to stabilise a collapsing object. We don't know of any mechanism that would produce such a pressure and save the thing. Black holes must exist. —RadRafe | t 10:08, 2 May 2005 (UTC)

plasma doesn't say anything directly about black holes. That's more the province of general relativity - which firmly predicts such objects. (So does Newtonian gravity, but it gives a different mass threshold.) Look near the end of the black hole article for an account of models of supermassive objects without singularities. The mainstream physics community supports black holes. (Actually, to be more precise, the theories of gravity don't say that black holes exist, they only say that they're possible and that if they exist they have certain properties observed as common to galactic nuclei and other dense astrophysical objects. Plasma physics might say something about the ways in which a dense star could collapse to form a black hole, but there are a lot of unknowns there.)

Even though nothing can escape from inside a black hole's event horizon, several sorts of radiation are emitted from just outside it. These include both the relativistic jets and Hawking radiation. The former have been observed, while the latter is still theoretical. (But is considered likely by mainstream physicists since the math looks good and the necessary observations are beyond current technology.)

The gravitational singularity at the center of a black hole might not be real, but that's not a big deal, since general relativity isn't expected to hold at lengths shorter than around the Planck length. (And singularity implies infinitesimal extent. I.e., some variant on general relativity might allow the event horizon without the singularity. Physicists find this idea comforting.

As for the definition of collimation: It means that the cone-shaped jets have a very narrow opening angle. The width is something like 2% of the height. The jets are very thin and long (for astronomical scales).SMesser 13:32, 11 May 2005 (UTC)