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I hope that this is a fun question for you physicists to answer.

Say you had a perfect piston - its infinitely strong, infinitely dense, has infinite compression ... you get the idea. Then you fill it with some type of matter, like water or dirt or something. What would happen to the matter as you compressed it indefinitely?

Edit: I'm getting some responses that it would form a black hole. For this question I was looking for something a little deeper, if you don't mind. Like if water kept getting compressed would it eventually turn into a solid, then some sort of energy fireball cloud? I'm not as concerned about the end result, black hole, as I am in the sequence.

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    $\begingroup$ A black hole would form, because eventually you'd surpass the matter's Schwarzschild radius. $\endgroup$
    – HDE 226868
    Jan 13, 2015 at 3:24
  • $\begingroup$ @HDE 226868: But would there be enough matter for the gravitational pull to be big enough to start pulling in other matter and accumulate? $\endgroup$
    – Time4Tea
    Jan 13, 2015 at 3:41
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    $\begingroup$ @Time4Tea Doesn't matter; any amount of matter can form a black hole if compressed enough. $\endgroup$
    – HDE 226868
    Jan 13, 2015 at 3:43
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    $\begingroup$ @Time4Tea You may recall some people were worried that the world be torn asunder when the LHC was turned on, since there was the possibility for miniature black holes to form for a fraction of a second, all from the smashing of individual particles. Not much matter is needed! $\endgroup$
    – TylerH
    Jan 13, 2015 at 14:16

4 Answers 4

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You asked for process. I'm assuming infinite material strength here, as in the piston cannot be stopped (infinite force on an infinite strength material that can resist infinite temperature).

  • Solids will be compressed, resulting in lots of heat as this happens (with infinite pressure, and infinitely strong materials and thus force, the matter will give), until they reach a liquid state, gaseous state, or start losing electrons and ionizing, or just stays solid all the way up to Electron Degeneracy - it depends greatly on the substance what happens here. With current realistic materials, the piston would break. Since it doesn't break, and there's infinite force behind it, the substance gets compressed and heated anyway.
  • Liquids will be compressed, resulting in lots of heat as this happens (with infinite pressure, and infinitely strong materials and force, the matter will give) into a gas, plasma, or Electron Degeneracy (depends on substance). With current realistic materials, the piston would break. Since it doesn't break, and there's infinite force behind it, the substance gets compressed and heated anyway.
  • Gaseous substances will then easily compress, resulting in lots of heating as they do, until they heat up enough that the electrons freely float among the nuclei, and you have just made a Plasma.
  • Now at a Plasma, the matter is slightly ionized (+1,+2) as the outermost electrons will have escaped and thus resulting in positive charges. The matter will continue to compress and heat
  • More compression, resulting in more heat. More electrons are too energetic to orbit the nuclei, resulting in higher positive charges (+3,+4 as allowable...).
  • More compression, resulting in more heat. More electrons are too energetic to orbit the nuclei, resulting in higher positive charges (+5,+6 as allowable...).
  • More compression, resulting in more heat. More electrons are too energetic to orbit the nuclei, resulting in higher positive charges (+7,+8 as allowable... until they're all gone). At some point you will surpass electron degeneracy pressure and form:
  • Electron Degenerate matter where no electron can orbit the nuclei, but now freely traverse the highly positively charged nuclei 'soup'. Keep adding pressure, and you'll form:
  • Proton Degenerate matter where only the repulsion of the protons is holding the nuclei apart. Keep adding pressure, and you'll form:
  • Neutron Degenerate matter where the electrons and protons join and cancel, leaving you with basically a huge neutral atom full of mostly neutrons, being held apart by the quarks. Keep adding pressure, and you'll (in theory) form:
  • Quark Degenerate matter where the quarks, or at least the standard up/down quarks, can no longer hold the pressure and perhaps combine/change form. Keep adding pressure, and in theory you might form:
  • Preon Degenerate matter which would sort of be like one big subatomic particle (though you might skip this one), and finally:
  • A singularity aka Black Hole
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    $\begingroup$ I've moved the active discussion on this post to chat. $\endgroup$
    – David Z
    Jan 14, 2015 at 7:23
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I'll convert my comment into an answer, because I think it answers the question:

A black hole would form, because eventually you'd surpass the matter's Schwarzschild radius.

The Schwarzschild radius of an object of mass $M$ is $$R=\frac{2GM}{c^2}$$ Compress any amount of mass into a sphere with a radius smaller than that and a black hole will form. Now, for small amounts of mass like this, it will most likely evaporate very quickly via Hawking radiation, but a black hole will form nonetheless.

Any amount of mass can form a black hole if strong enough forces are acting on it. Here, the force is not gravity - at least, not the force causing it to undergo the collapse - but the force applied by the piston.

Regarding the edit - If you compress liquid water enough, then it most likely will not turn solid. You can see this by looking at a phase diagram, which shows how the state of a compound changes with temperature and pressure. Here's an example of a generic phase diagram:

Example

Now check out water's phase diagram here. Water has a chance at becoming solid only in a very narrow range of temperature and pressure, if it starts off as a liquid.

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  • $\begingroup$ So liquid water has a chance of becoming solid, but will it always eventually turn into a supercritical fluid, no matter the temp? What happens once the supercritical fluid gets compressed even further? Will it just stay in that state until it forms a black hole? $\endgroup$
    – Mardymar
    Jan 13, 2015 at 5:21
  • $\begingroup$ I reread the website you linked. It appears that, given enough pressure, it may turn into a supercritical fluid, but it will eventually become a substance the website referred to as c2/m (metallic). This seems like a type of solid. What happens once this gets compressed even further? Will it just stay in that state until it forms a black hole? $\endgroup$
    – Mardymar
    Jan 13, 2015 at 5:36
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    $\begingroup$ @user3925445 to get a supercritical fluid you need high pressure and high temperature - check the phase diagram again. $\endgroup$
    – user253751
    Jan 13, 2015 at 5:44
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    $\begingroup$ @HDE226868, for any reasonable starting temperature, isothermal compression will eventually produce ice ten. $\endgroup$
    – Mark
    Jan 13, 2015 at 11:34
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    $\begingroup$ The phase diagram you link to does not show what you say it shows. Increasing the pressure sufficiently will always turn water into a solid, no matter the temperature. $\endgroup$
    – N. Virgo
    Jan 13, 2015 at 12:22
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Then you fill it with some type of matter,

Why do You want to do that? Your piston is ", infinitely dense, " so You are going to compress matter with a black hole piston :=)

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    $\begingroup$ Good catch! I interpreted that as 'infinitely strong' in the spirit of what I thought was being asked, but you are correct here. It would all get sucked into the black hole of the piston first! $\endgroup$
    – Ehryk
    Jan 13, 2015 at 15:56
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Presumably, it's going to be similar to the Big Bang in reverse, which is also what happens at the singularity of a black hole or any situation where matter is continuously compressed.

(Beyond a certain point, we don't really know.)

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  • $\begingroup$ I'd appreciate if whoever downvoted could explain why. I know its a bit of a vague answer, but did I say something wrong? $\endgroup$
    – Time4Tea
    Jan 13, 2015 at 15:57
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    $\begingroup$ Nothing wrong, but it's a worse quality answer covering the same ground as an older one (I'm not the downvoter). $\endgroup$
    – Joshua
    Jan 13, 2015 at 18:05
  • $\begingroup$ @Joshua: Well, I know it doesn't provide much in terms of detail, but I thought it was worth adding that, beyond a certain point, we don't know what happens as matter is compressed, in the same way that we don't know exactly what happens at the singularity of a black hole. $\endgroup$
    – Time4Tea
    Jan 13, 2015 at 18:27

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