Proof that micro black holes can't exist?

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Discussion Overview

The discussion centers around the possibility of micro black holes existing, with a focus on theoretical constraints derived from quantum mechanics and the uncertainty principle. Participants explore the implications of these constraints on the mass and energy associated with black holes, particularly in the context of Planck mass and Planck time.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant presents a reasoning based on the uncertainty principle, suggesting that the maximum mass that can be created from vacuum fluctuations is half the Planck mass, which they argue implies micro black holes cannot exist.
  • Another participant questions the initial claim by introducing the concept of black holes moving at relativistic speeds, implying that energy considerations may differ in such scenarios.
  • A later reply emphasizes the need to reverse inequalities in the uncertainty principle, suggesting that the initial reasoning may require reevaluation.

Areas of Agreement / Disagreement

Participants express differing views on the implications of the uncertainty principle for the existence of micro black holes. There is no consensus on whether the initial reasoning is valid or if relativistic effects could allow for different outcomes.

Contextual Notes

Participants reference specific assumptions about the Planck mass and Planck time, but these assumptions are not universally accepted or agreed upon. The discussion also highlights potential gaps in understanding quantum mechanics among participants.

zeromodz
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I was playing around with some equations and I found a reason why I think micro black holes cannot exist. This proof requires a few assumptions which I have tended to find to be a scientific consensus. They are the following.

1) The smallest mass a black hole can have is the Planck mass which by definition will give the schwarchilds radius of the black hole the Planck length.
2) The smallest meaningful increment of time in the universe is the Planck time.

Lets start with the uncertainty principle.

ΔXΔP <= h / 4π

This can also being written as.

ΔEΔT <= h / 4π
ΔE <= h / 4πΔT

This tells us that the amount of energy uncertainty created from the vacuum is inversely proportional to the time. Now let us change our units of energy to mass by dividing the equation by c^2

Mtotal <= h / 4πΔTc^2

The maximum amount of mass that can be created from nothing out of the uncertainty of the vacuum can now be written as the following.

Mtotal = h / 4π(Tplanck)c^2
Mtotal = (6.626 * 10^-34) / ((4π)(5.39 * 10^-44)(299792458)^2)
Mtotal = 1.088 * 10^-8 kg

The Planck mass is 2.17 * 10^-8 kg. So it turns out the maximum amount of mass that can be created from nothing for 10^-44 seconds is exactly half the Planck mass. Am I missing a factor of two anywhere? Or is it just Planck masses and micro black holes cannot be created from the uncertainty principle? Thanks
 
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Well, what if you have a black hole moving at relativistic speeds? (so E =/= mc^2) :P

I don't know quite enough about QM to comment about anything else...
 
n1person said:
Well, what if you have a black hole moving at relativistic speeds? (so E =/= mc^2) :P

I don't know quite enough about QM to comment about anything else...

Well, at least you tried.
 
n1person said:
Well, what if you have a black hole moving at relativistic speeds? (so E =/= mc^2) :P

I don't know quite enough about QM to comment about anything else...

You just go in the reference where it is at rest (which exist becausse M_{BH} &gt; 0)



zeromodz said:
I was playing around with some equations and I found a reason why I think micro black holes cannot exist. This proof requires a few assumptions which I have tended to find to be a scientific consensus. They are the following.

1) The smallest mass a black hole can have is the Planck mass which by definition will give the schwarchilds radius of the black hole the Planck length.
2) The smallest meaningful increment of time in the universe is the Planck time.

Lets start with the uncertainty principle.

ΔXΔP <= h / 4π

This can also being written as.

ΔEΔT <= h / 4π
ΔE <= h / 4πΔT

This tells us that the amount of energy uncertainty created from the vacuum is inversely proportional to the time. Now let us change our units of energy to mass by dividing the equation by c^2

Mtotal <= h / 4πΔTc^2

The maximum amount of mass that can be created from nothing out of the uncertainty of the vacuum can now be written as the following.

Mtotal = h / 4π(Tplanck)c^2
Mtotal = (6.626 * 10^-34) / ((4π)(5.39 * 10^-44)(299792458)^2)
Mtotal = 1.088 * 10^-8 kg

The Planck mass is 2.17 * 10^-8 kg. So it turns out the maximum amount of mass that can be created from nothing for 10^-44 seconds is exactly half the Planck mass. Am I missing a factor of two anywhere? Or is it just Planck masses and micro black holes cannot be created from the uncertainty principle? Thanks
Well, first you need to reverse all the inequalities: It's \Delta X \Delta P \geq \hbar and \Delta E \Delta t \geq \hbar.
 
Last edited:

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