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In general, when a star runs out of nuclear fuel, gravity gets the upper hand and the material in the core is compressed even further and creates black holes. I am clear till here.

Now the question is: Does that depend on the mass of the star (or object)?

Naturally, the more massive the core of the star, the greater the force of gravity that compresses the material and easy to create Black Hole. For smaller stars, when the nuclear fuel is exhausted and there are no more nuclear reactions to fight gravity, the repulsive forces among electrons within the star eventually create enough pressure to halt further gravitational collapse. The star then cools and dies peacefully.

In science videos and discussions is said that we can create black holes from any object. For example, if we are able to compress Earth to the size of the tennis ball, can we then create a black hole?

Isn't the nuclear fusion / reaction necessary to create a black hole? Of course, to fight against gravity we may require some kind of energy in this case, Nuclear reactions. But I am generally concerned like, does Nuclear Reaction is only to fight gravity, it does not play any other role in creating Black Hole.

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  • $\begingroup$ "Can we" ? Who are you calling a star? $\endgroup$ Feb 15 at 15:44
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Do you mean, "Can we in principle", or just, "Can we..." ?

The answer to the latter is no. We have no technology to create black holes. It was a remote possibility that was considered when creating the high energy densities in the LHC, but in practice the energies aren't high enough.

Can we in principle do it? The answer is yes. If you can squash enough mass (or energy) into a very small volume then the inevitable consequence is a black hole.

Most would say that the volume in question is governed by the Schwarzschild radius, $r_s$ which is roughly 3km multiplied by the mass in solar units. Thus for an Earth mass $r_s$ is about 1 cm.

Actually the radius within which collapse to a black hole is inevitable is a little bit larger because even the "hardest" equation of state, where the speed of sound equals the speed of light, cannot resist collapse at radii below about $1.5 r_s$.

The problem is that to compress materials this much would be incredibly difficult. For the example of an Earth mass, we are talking densities of order $10^{30}$ kg/m$^3$. But (long) before you got to that stage, yes you would have the problem of overcoming the nuclear fusion reactions would be initiated that would oppose your compression (ie you would end up making a mini-star before you could get to a black hole). Because the Schwarzschild radius depends linearly on mass, then less massive black holes need to be even denser. However, we are again talking about "in principle". So assuming compression could overcome the various opposing forces, then a black hole could be formed.

It really doesn't matter what the black hole is made of. In a star, the sequence of nuclear fusion events is a consequence of the physical conditions in the stellar interior. It is not anything that is required for black hole formation.

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Kind of a quick answer, if you don't mind.

Can we compress any object to create black Holes?

The pressure at the bottom of the ocean is enormous, it would kill a person in a fraction of a second, but it's tiny compared to the pressure in the center of the earth, and that's tiny compared to the pressure in the center of Jupiter, and that's tiny compared to the pressure inside the sun, and the pressure inside of the sun is also, tiny-tiny-tiny compared to the pressure required to create a black hole.

In the science videos and discussions, they say that, we can create Black hole from any object, i mean for example, if we are able to compress EARTH to the size of the Tennis Ball, then we can create Black Hole, Is it True?

I think it's closer to the size of a golf-ball, but yes, that's true. But it's also impossible. There's no known way to do that. We probably don't even have the means to crush a single car to the size of a golf-ball or tennis-ball and if we did, it would just rebound once we removed the compression force. Matter is enormously difficult to crush anywhere close to that much. That's why it only happens in the core of large stars. That's the only place where there's enough pressure.

does Nuclear Reaction is only to fight gravity, it does not play any other role in creating Black Hole.

Nuclear reaction doesn't play a role in creating a black hole. A black hole by definition, is gravity strong enough that the escape velocity is greater than the speed of light. Nuclear energy doesn't come close to that. Nuclear fusion prevents black holes form forming when there's enough matter for a black hole to form, but that's about it. Black holes can't happen without an enormous amount of mass, about 3 solar masses and no sustained nuclear fusion.

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Short answer: This is not known to be possible because the only place where there is so much pressure is in the core of an extremely massive star. Also, if the star is too massive the pressure may not be enough, as in the case of stars with 140-250 solar masses. Those stars explode in a pair-instability supernova, or in short, the star explodes, leaving no remnant other than the explosion. After that mass range we go back to black holes.

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  • $\begingroup$ Welcome on the Astronomy SE! Afaik the "no remnant" case is a narrow part of the configuration space, it also requires low (or high?) metallicity, too. $\endgroup$
    – peterh
    May 5 '20 at 21:13
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Theoretically YES But practically NO. In theory if you can compress any matter to its schwarzschild radius you can create a black hole.

But for now we don't have that technology to compress any object to that extent.

For making a black hole of approximately 2cm radius you have to compress whole earth.

For further info https://www.britannica.com/science/Schwarzschild-radius

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When referencing information about black holes, remember all we have are a few limited observations. None of which are from within the event horizon. Nothing visual other than a few instances where a presumed to be black hole is interacting with its surroundings, giving us something observable. The new gravitational measuring devices we have are the only next possible insight into what black holes do/are. A few things I would ask the entire observing population to consider, my own hypothesis. If there is such a thing as a singularity, and two "things" can occupy the same space at the same time, then why not three, or four, or 65 million? Assuming there is a singularity that we have never before observed, and that it is due to this "singularity" that we have black holes, is simply unfounded, and I would say... imaginative. A fabrication, just like everything else we assume is going on behind that veil of darkness. But what if we assume there is no such thing as a singularity? I propose that a singularity is impossible. Within the confines of this universe, a singularity does not exist. Two objects with mass and volume, occupying spacetime, cannot exist in the same space at the same time, otherwise, spacetime ceases to exist. Instead, I suggest the thought that what exists behind that event horizon is nothing more than the most densely packed ball of quarks, and possibly smaller sub-quark particles or forces, stacked in a near perfect crystalline structure with electrons, positrons, any and all other charge/forces with a net quantum value that exerts a gravitational pull in direct proportion to the mass of the center of the black hole, which directly coincides with the size of the event horizon and all other observable/measurable indications. If a singularity is assumed to be possible, then why would any black hole change diameter? You could say that the gravity doesn't change, because the mass hasn't changed, but then why assume a singularity? Simple answer is, we fantasy nerds love the word and the idea it represents. Like being able to beam up to the USS Enterprise, or shoot someone with an anti-matter gun. It's a flight of fancy and fantasy. If we assume that the center of a black hole is a crystalline structure, due to the strong gravitational forces, quantum gravity of course, then we resolve the issues surrounding this fantasy of the existence of a singularity, and we can also extrapolate that certain sub-quark particles may be arranged in such a fashion that causes specific observable properties of a black hole to exist, such as rotation, accelerated rotation, north and south poles, the possibility of radiation, whether it be hawking radiation or simply the loss of particles due to rotational forces actually shearing off and accelerating of particles faster that the gravitational attraction can hold them in. Of course that may be more fantasy as well. Who knows? Another assumption we like to make is that only stars of a specific mass can become black holes. I think this is also a misnomer of sorts. A lot of "theory" is that electron pressure and nuclear reactions create forces that are able to stave off gravitational collapse into a black hole. I think this is assuming some fantastic "quantum" under the "perfect" conditions for such an event to happen, and we also assume that the long slow road to black hole creation is through a specific set of circumstances. If a specific "mass" is required, what happens if a star of a specific mass, just under the threshold let's say, gets hit by an asteroid? does the added mass instantly cause a gravitational collapse and instantaneous black hole formation? Seems stupid to assume yet, quantumly, this should in fact happen. Not only that but an impact to the outside of a neutron star of sufficient mass should instantly cause a singularity in the core, and instantaneous creation of a black hole. I would say, black holes are NOT the result of such gigantic masses, but instead, are a result of the inward shockwave of such a magnitude that in most cases, as if creating a diamond in a spherical hydraulic press, an event of widespread subatomic particle breakdown occurs, a reconfiguration of super hot quark and sub-quark particles arrange themselves like a diamond taking shape, and a crystalline core is created of such an extreme density that it exerts a gravitational pull within such a confined and CONCENTRATED space, directly around the crystalline structure, that light, approaching from a specific angle, gets pulled inward and spirals in to join the crystalline center. In fact, if a black hole consumes everything by gravity, then should it pull in positrons, or anti-matter particles, there should be a decrease in mass/matter resulting in a slowly degrading black hole that, over millions or billions of years, will loose mass to the point where it reverts back to something more akin to a neutron star. Is it possible neutron stars or quasars are older black holes that have lost mass to the point where they could no longer conceal their mannerisms? Food for thought. Oh, and black holes do not exert "pressure" in the traditional sense. They exert Anti-gravity. Everything with mass has gravity, and anti-gravity, at a point far beyond the gravitational influence. Even you and I. But due to the super intense gravity concentrated around the crystalline core of a black hole, we can observe the anti-gravity repulsion "field" surrounding a black hole at an exponential distance from the core. Only due to the magnitude of the gravity, can we observe the anti-gravity.

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    $\begingroup$ This might be an interesting answer but it currently is a "wall of text" with no breaks or paragraphs, so it's too hard to read to try to figure out if your answer to "Can we compress any object to create black Holes?" is "Yes" or "No". Could you adjust it a bit and perhaps add a "tl:dr" to the beginning to let us know what the short answer is? Thanks! and welcome to Stack Exchange! $\endgroup$
    – uhoh
    yesterday

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