What I mean by conventional, is that chemical, mechanical and electromagnetic heating are in bounds, but not nuclear.

And I assume that there a limit to how much a material can be heated due to:

  • The lack of a material that can mechanically confine it
  • Or the lack of materials to generate sufficient electrical current to magnetically confine it
  • The lack of materials to generate sufficient chemical/electromagnetic etc energy to funnel into it

Sorry if the question seems vague, I will attempt to clarify if asked the right questions in the comments.

Note: this is a totally different question than: Is there a limit to how hot an object can get? which is asking about theoretical thermodynmic limits.

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    $\begingroup$ Why does it need to be confined? Does the material need to be in thermodynamic equilibrium? Why rule out nuclear? $\endgroup$ – Jon Custer Dec 19 '18 at 17:21
  • $\begingroup$ @JonCuster: Perhaps it doesn't. I'm just assuming that in order to get to ultra high temperatures, we need to concentrate energy somehow. I rule out nuclear because this allows us to release huge amount of energy from the material itself and in that case, we inevitably up up talking about astrophysical-scale object. I'm asking more about heating something than consuming it. $\endgroup$ – ThePopMachine Dec 19 '18 at 18:44
  • $\begingroup$ Last I checked a nuclear weapon was not astrophysical in scale, and does some pretty serious heating to its contents. A tokamak gets to millions of degrees, does that fit? $\endgroup$ – Jon Custer Dec 19 '18 at 19:15
  • $\begingroup$ What is your line for "macroscopic?" LHC hit 5.5 trillion K a few years back. I think the primary limiting factor for how hot a macroscopic object can get is that large hot things just aren't all that valuable to us, so we don't tend to make things that can contain them. $\endgroup$ – Cort Ammon - Reinstate Monica Dec 19 '18 at 21:08
  • $\begingroup$ @JonCuster: No, a nuclear weapon is not astrophysical in scale, but I'm eliminating nuclear energy for the purpose of the question. I gave the reason I'm interested in conventional means. It doesn't imply that all non-conventional means are astrophysical in scale; just that I'm not interested in nuclear means because that changes the question completely and it becomes one about stars, etc. $\endgroup$ – ThePopMachine Dec 19 '18 at 23:17

What you ask is actually not a physics question. It's an engineering question. There's really not all that much of a difference physics wise between a ball of protons and a marble.

Of course, from an engineering perspective, they are monumentally different.

Consider this line of reasoning. The LHC hit 5.5 trillion degrees C a few years back. It used roughly 10^-16kg worth of protons to do so (ignoring relativistic effects). A grain of sand is roughly 10^-5kg, so we will need to scale up the LHC by 10^11. We'll start by assuming that scaling is linear. It might not actually be linear when reality gets in the way.

The LHC uses about 120MW of power. Its biggest limitation is that it quenches the superconducting magnets a few times a day, and has to start over We'll say 4 times. That's 6 hours to do an experiment to generate the highest heats possible. 6 hours at 120MW is about 2.5TJ of energy. So we used 2.5TJ of energy to heat up that little tiny mass to 5.5 trillion degrees.

if we scale that, 2.5TJ * 10^11 is about 10^23 J of energy. From one of my favorite Wikipedia pages, Orders of Magnitude (Energy), that's roughly 10 times the available fossil fuels.

Since you explicitly forbid nuclear power, and described your intent of avoiding including stars, we're going to have to work with what we have. Fossil fuels it is.

So that should be enough to show that this is really an engineering problem, not a physics problem. Very roughly, you should be able to get an object the size of a grain of sand up to about 500 billion degrees using similar techniques to the LHC, assuming they scale linearly. In practice, I'm sure we'll find the LHC doesn't scale this way. But also in practice, I'm assuming you wont be permitted to consume the planet's entire fossil fuel reserves in the effort to make something really hot.

So it's not a physics question, and maybe it's not even an engineering question. Maybe its a politics question!


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