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5 votes

Different Bekenstein bound equations – what’s the difference?

They seem to differ only on the choice of units. The second version uses units with $k = 1$ and the last equation uses units with $k = \hbar = c = 1$. These sorts of unit systems are very common in ...
Níckolas Alves's user avatar
3 votes

Gravitational collapse - proof that energy dissipation is required?

The virial theorem tells us that for an isolated cloud (no external pressure, magnetic fields or rotation) that $$2K + \Omega = 0\ , $$ where $K$ is the kinetic energy of the cloud particles and $\...
ProfRob's user avatar
  • 133k
2 votes

Feasibility of entropy at zero temperature

The first and most important part to this question is the link By Symmetry points out in the comments, which includes the following: The third law is equivalent to the statement that It is impossible ...
Cort Ammon's user avatar
  • 50.2k
1 vote

Why does entropy obey the superposition principle?

I think you are confusing the causes and consequences here. First of all, Boltzmann did not introduce the concept of Entropy $S$, Clausius did and it was an extensive additive property by definition (...
John's user avatar
  • 3,872
1 vote

How much information is encoded in a ball on a field?

Just a rough estimate. Let's take a standard soccer field dimensions $100~\text{yard} \times 50~\text{yard}$. Assuming a ball can be placed anywhere within this field with a $\delta x = 1~mm$ ...
Agnius Vasiliauskas's user avatar
1 vote

At what size of matter does the second law of thermodynamics breakdown?

(Not an expert) In a statistical experiment the noise (i.e., the random fluctuations) is also known as Poisson noise, and it can be shown to be proportional to $1/ \sqrt{N}$, where $N$ is the number ...
Allure's user avatar
  • 21.3k
1 vote

High fidelity implies low entropy

This is easiest to see if you diagonalise the state \begin{align} \rho = \sum_j p_j |\phi_j \rangle\langle \phi_j|, \end{align} where the $|\phi_j\rangle$ are orthogonal and normalized, and the $...
ors's user avatar
  • 549
1 vote

Is time travel a violation of second law of thermodynamics?

At least one serious physiciat seems to think that closed timelike curves would indeed violate the second law of thermodynamics, although his argument is not as straightforward as you presented it and ...
Ron Inbar's user avatar
  • 131

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