How can we establish the age of a black hole? I think that black holes are the oldest and the most massive objects in the Universe. Am I right? Since nothing gets out from a black hole we cannot know the age of the matter inside it. Am I right?
If it is true that they are the oldest objects in the universe, knowing their age may give us information about the age of the universe, and, MAYBE, about when the Big Bang occurred. For instance, the Big Bang couldn't have occurred after the black holes were formed. Also, it may be that a black hole is a shard from the the object that exploded and produced the Big Bang.
I appologize, ny question may seem naive, cosmology is not my domain of competence.
Black holes can have very different masses, from "microscopic" size (e.g., the mass of an electron) to one stellar mass to the mass of billions of stars. For different types of black holes, see https://en.wikipedia.org/wiki/Outline_of_black_holes#Types_of_black_holes,_by_size .
The mass of large black holes can be estimated from the gravitational force of a black hole on nearby masses, especially on stars. When observing the orbits of stars around a massive black hole, its mass can be calculated.
Not all black holes are old ones. A stellar black hole can be very young, when the original star has collapsed only recently. Supermassive black holes in the centers of galaxies are thought to have the same age as the surrounding galaxy. And the age of a galaxy can be estimated from the properties of its stars.
The previous paragraph is related to when the black hole itself was born. Your question about the "age of the matter inside" a black hole is quiet another one. We can assume that all matter in the universe and thus also inside a black hole is as old as the universe itself. However, matter can change its type, and when a black hole is formed or when matter falls into an existing black hole, the type of its matter changes considerably. Therefore, when you ask how old is the black hole matter in its current state, the answer depends on whether the matter was there when the black hole was formed or whether is fell into the black hole later.
Popular introductions are, e.g.:
https://www.nasa.gov/audience/forstudents/k-4/stories/nasa-knows/what-is-a-black-hole-k4.html
https://solarsystem.nasa.gov/news/1068/10-questions-you-might-have-about-black-holes/
https://www.quora.com/How-can-we-determine-how-old-a-black-hole-is
Yes-cf. the paper by Oppenheimer and Snyder, Phys. Rev. 56, 455 (1939) who did just such a calculation-what they did show is that the time for collapse, for an outside observer is well-defined. The mass is, similarly, well-defined for the outside observer, as is the case in general relativity.
Black holes aren't, however, either the most massive, nor are they the oldest objects in the Universe, simply because it's possible to have a very massive star, that hasn't collapsed to a black hole yet.
Once the collapse has occurred, however, the notion of the age of a black hole doesn't make sense-within general relativity, of course. A new time scale appears when Hawking radiation becomes relevant.
Dear Sofia D. Wechsler Black holes is not real, it just is pseudoscience remark, it never been observed or seen, simply it is just theory of a theory. Similar to All Mr. Einstein theories.
You might see picture of BH 2019 - 2021 all are computerized by artist.
Our universe is much complete very organized entity, look around yourself. or read this article.
https://www.academia.edu/43351041/How_the_Quantum_Universe_Works
regards
Stam Nicolis
Dear Stam, please tell me more. Are there black holes as old as the estimated age of the universe?
Are there stars, as you say, on the brink of collapsing to a black holes? Maybe, you know examples? It's interesting to know their age.
With kind regards
The opinion that black holes and Einstein's theories are "pseudoscience" does not correspond to the current state of physical and astronomical sciences. The assertion that the published picture of a black hole was "computerized by artist" is a conspiracy theory similar to the claim that astronauts have never been on the moon.
A black hole is a place in space containing an enormous amount of mass packed very tightly together. These objects have so much mass — and therefore gravity — that nothing can escape them, not even light. https://t.co/NLZseL8kA3
Jinan Abdul Ameer Abbas from the point of view of black holes described by general relativity, black holes are ill defined objects. the evolve out of collapsing stars, whose masses, due to general relativity, crushes to a point, which gives infinite density, which is ridiculous and only shows the limits of general relativity. black holes pave the way to a novel theory of gravity.
Preprint A Heuristic View on the Composition of Space
Preprint A New View on the Composition of Matter
to calculate its mass, is no problem. also to calculate its volume. see the articles of maulik parikh
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