I can't find anything related on Google. I hope this is the correct site to ask this question.

I have been thinking about Randomness. Basically, generating randomness using a Computer Program. It is impossible without a source of randomness. The entropy of the numbers is limited to what the source provide and its reliability.

So you can't get random numbers out of thin air. Does this mean that randomness requires 'energy'?

Sure energy is not enough to get real random numbers but is it a requirement for getting them?

  • $\begingroup$ Given your profile you already know about energy usage. Is there something more specific you're asking about entropy /randomness? Are you talking of electricity, or Joules, electronvolts etc? $\endgroup$
    – Paul Uszak
    Apr 16, 2018 at 20:23
  • $\begingroup$ And you can get random numbers from thin air (vacuum) using zero point energy effects on photons, but that's pretty clever stuff. $\endgroup$
    – Paul Uszak
    Apr 16, 2018 at 20:24

2 Answers 2


Everything that happens on computers requires some energy. This includes the very act of looking up random values from any source.

There is a mythical beast called reversible computing which is basically computing without using up energy. It's unclear whether it can exist at all; but laws of physics (as we currently understand them) imply that reversible computing must also be logically reversible. This is known as Landauer's principle: if some information is erased in a process, then entropy (the physical notion) rises and this requires usage of some energy. Thus, computing a hash function necessarily requires some energy.

Note that this notion is about the conservation of information: it's not obtaining randomness that matters; it's about what you do with it.


Of course it does. Computing a (pseudo)random number requires running an algorithm, which takes energy. Usually rendered in the form of AC power to the machine.


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