0
$\begingroup$

What is the consensus on whether or not nature actually has functional infinities such as an absolute singularity, or the multiverse itself as a whole, or even some potential for reality always existing in some state (a context from which spacetime or other can emerge).

Given renormalization for instance to deal with infinities that come up in quantum mechanics, does the act of doing so mean we don't think those can actually be a physical reality?

Improve this question
$\endgroup$
14
  • 1
    $\begingroup$ Do you mean like the infinite density at the center of a black hole? Or the infinite force two point particles would exert on each other if infinitely close to each other? Or the possibly infinite size of the universe? If so, no. The solution to the General Relativity field equations give an infinite density, but this shows we need a better theory than GR. If you put charges close enough together, you need quantum mechanics to describe the forces, and the particles turn out not to be classical points. We can't see how big space is. expect it is at least 500 time bigger than the part we see. $\endgroup$
    – mmesser314
    Commented Feb 25 at 14:59
  • 1
    $\begingroup$ Related: physics.stackexchange.com/q/24934/2451 , physics.stackexchange.com/q/590774/2451 , physics.stackexchange.com/q/455726/2451 , physics.stackexchange.com/q/261340/2451 and links therein. $\endgroup$
    – Qmechanic ♦
    Commented Feb 26 at 9:13
  • 1
    $\begingroup$ Two more related questions. $\endgroup$
    – J.G.
    Commented Feb 26 at 9:24
  • 1
    $\begingroup$ It's a good question, and I have voted to reopen, but I suspect it's one of those questions that is a matter of opinion. For what it's I don't believe infinities exist in the real world apart possibly from the size of the universe. But other physicists may have different opinions and there is no way to tell who is correct. $\endgroup$
    – John Rennie
    Commented Feb 26 at 9:27
  • 1
    $\begingroup$ Rule of thumb is infinities imply an incomplete theory. Consider the Ultraviolet Catastrophe. The infinities of the Schwarzchild solution to Einstein's field equations at the event horizon were an artifact of coordinates. Renormalization of Quantum Field Theory also gets rid of infinities in a way that can't be done with gravity. $\endgroup$
    – R. Romero
    Commented Feb 26 at 9:34

2 Answers 2

Reset to default
3
$\begingroup$

Sensible physicists never believe idealized mathematical models. We employ them to capture (sometimes extremely successfully) aspects of real phenomena, but mathematics isn't real. It exists only in the human mind.

Improve this answer
$\endgroup$
15
  • $\begingroup$ Whether or not this is true, that is a philosophical position that the physics itself does not require you to embrace. $\endgroup$
    – David C.
    Commented Feb 26 at 15:25
  • $\begingroup$ @DavidC.The history of physics does. Galileo's experiments remain as fundamental physics even though the mathematics of gravity theory have changed drastically. Mathematical physics is a shifting story we tell about the phenomena: who sanely believes it? $\endgroup$
    – John Doty
    Commented Feb 26 at 15:32
  • $\begingroup$ Well, for instance, I think a case could be made that Einstein really believed his General Relativity in such a way. $\endgroup$
    – David C.
    Commented Feb 26 at 15:34
  • $\begingroup$ @DavidC. Einstein's beliefs seem to have been a bit shifty and unstable (this is not a criticism). $\endgroup$
    – John Doty
    Commented Feb 26 at 15:37
  • $\begingroup$ @DavidC. Einstein saw GR as an incomplete component of a more comprehensive field theory, and attempted to construct one. $\endgroup$
    – John Doty
    Commented Feb 26 at 15:41
2
$\begingroup$

Experience suggests infinities aren't real. Misuse of The Partition Theorem implied runaway energies at certain frequencies due to heating, The Ultraviolet Catastrophe. By some primitive analyses, the night sky should be super bright. It isn't because the universe is expanding and its age is finite. Infinities disappear in QFT, giving us the most accurate theory we have. The infinities at the event horizon of a black hole vanish with a change of coordinates.

As to arguments that infinity exists with some physical manifestation, the center of a black hole has infinite density, but there's reason to believe that is suspicious apart from suspicion of infinities. General relativity is silent on the uncertainty principle which is a bad sign. Apparently some physicists believe the singularity truly has infinite density.

Due to a theorem from Paul Dirac, if there is a magnetic monopole anywhere in the universe, it is expected that electric charge would be quantized. If it doesn't matter where that monopole is, does it suggest it's effects propagate at infinite speed?

Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.