3 ms·

I've seen mention before of the Carnot efficiency of Dyson spheres, but what about Landauer efficiency? Assuming the DS is powering a bunch of computers, and as

I've seen mention before of the Carnot efficiency of Dyson spheres, but what about Landauer efficiency? Assuming the DS is powering a bunch of computers, and assuming sufficiently advanced technology that these computers approach the limits of physics (reasonable for a Type 2 civilization imo), then their computers will use power proportional to kT. The colder the computer, the less power it uses. https://en.wikipedia.org/wiki/Landauer%27s_principle https://en.wikipedia.org/wiki/Landauer%27s_principle This provides another thermodynamic reason to make a Dyson sphere as large as possible.

O5vYtytb 9y ago
Doesn't this also assume a computer similar to our own? How would this principle apply to a biological computer for example?
- lann 9y ago
  > Doesn't this also assume a computer similar to our own? No. It is about abstract computation, which is based on (our best understanding of) theoretical physics.
- Armisael16 9y ago
  The Landauer limit applies to all non-thermodynamically reversible changes of state in a system. I don't know how your biological computer works, so I can't say 100% that it applies - but it probably does.
- SAI_Peregrinus 9y ago
  The Landauer principle applies to any computer made of matter utilizing energy (in a non-thermodynamically reversible fashion). So it applies just fine to biological computers, quantum computers, and even mechanical computers! It's a result in quantum information theory, and doesn't have anything to do with the overall type of computer used. It just determines how much energy it takes to change the state of a quantum (particle), at a minimum. Things like changing the polarization of a photon or the spin of an electron.
pmoriarty 9y ago
The Wikipedia article you also has this to say about Landauer's principle: "The principle is widely accepted as physical law; but in recent years it has been challenged^[how?], notably in Earman and Norton (1998), and subsequently in Shenker (2000)^[10] and Norton (2004,^[11] 2011^[12]), and defended by Bennett (2003)^[1] and Ladyman et al. (2007).^[13]" So even now, a mere 56 years after its proposal, this principle is coming in to question. How much more questionable would it be after millions or even billions of years of physics research that alien civilizations may have under their belt by the time they start building these sorts of Dyson spheres? How many revolutions in physics knowledge might they have had by that point? They may be able to perceive reality in completely different ways than we do, and have unimaginable intelligence at their disposal. It is certainly fun to speculate, but I personally find it very difficult to put limits on what beings like that might be capable of, especially when those purported limits are the results of mere human thought.

O5vYtytb 9y ago

Doesn't this also assume a computer similar to our own? How would this principle apply to a biological computer for example?

lann 9y ago
> Doesn't this also assume a computer similar to our own? No. It is about abstract computation, which is based on (our best understanding of) theoretical physics.
Armisael16 9y ago
The Landauer limit applies to all non-thermodynamically reversible changes of state in a system. I don't know how your biological computer works, so I can't say 100% that it applies - but it probably does.
SAI_Peregrinus 9y ago
The Landauer principle applies to any computer made of matter utilizing energy (in a non-thermodynamically reversible fashion). So it applies just fine to biological computers, quantum computers, and even mechanical computers! It's a result in quantum information theory, and doesn't have anything to do with the overall type of computer used. It just determines how much energy it takes to change the state of a quantum (particle), at a minimum. Things like changing the polarization of a photon or the spin of an electron.

pmoriarty 9y ago

The Wikipedia article you also has this to say about Landauer's principle: "The principle is widely accepted as physical law; but in recent years it has been challenged^[how?], notably in Earman and Norton (1998), and subsequently in Shenker (2000)^[10] and Norton (2004,^[11] 2011^[12]), and defended by Bennett (2003)^[1] and Ladyman et al. (2007).^[13]" So even now, a mere 56 years after its proposal, this principle is coming in to question. How much more questionable would it be after millions or even billions of years of physics research that alien civilizations may have under their belt by the time they start building these sorts of Dyson spheres? How many revolutions in physics knowledge might they have had by that point? They may be able to perceive reality in completely different ways than we do, and have unimaginable intelligence at their disposal. It is certainly fun to speculate, but I personally find it very difficult to put limits on what beings like that might be capable of, especially when those purported limits are the results of mere human thought.