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Please link if there is any preexisting information about this subject, or lmk if there's a more appropriate forum for the question.

I am wondering if it is possible to record information (could be the text of a book, or something as simple as a number) in a way that it could never be destroyed or forgotten.

My first thoughts were:

  • Blockchain (but what if the earth & all its computers were to explode)
  • Voyager golden record (but what if they were hit by meteors)

I believe information like this exists, for example the value of pi. But I don't know if it is possible to record new information with such properties.

So, any thoughts would be appreciated :)

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    $\begingroup$ What is the definition of information you want to be recorded permanently? $\endgroup$ – GiorgioP Apr 16 at 14:56
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    $\begingroup$ Technically thermodynamics guarantees that information is never destroyed. Even in the case of something falling into a black hole. This doesn't mean you can retrieve said information as it disperses and changes form throughout the universe. $\endgroup$ – R. Rankin Apr 17 at 3:22
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If you're considering cosmological time scales, such as beyond the destruction of the Earth, then it currently appears that it most likely isn't possible to store information permanently. The ultimate fate of the universe isn't known with certainty, but it currently appears that there will be a heat death of the universe, beyond which no useful work can be performed to do error correction of stored information, which will always tend to decay due to entropy.

However, there will still be things which will continue to be true, despite an ultimate inability to record information about those truths. For example, the number pi will continue to exist abstractly, and will have the same mathematical properties, even after there are no longer any intelligent beings who can contemplate the nature of pi, and there is no longer any way to record the value of pi to some number of digits in some number system.

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  • $\begingroup$ What happens to an electro-magnetic wave "in the long run"? It quickly gets weaker with distance but is it ever completely "destroyed"? $\endgroup$ – d-b Apr 17 at 0:30
  • $\begingroup$ @d-b It gets drowned out in the background radiation and noise. Not to mention energy is quantized so it would be the same way if you dilute something enough there are eventually no more molecules of the original thing in most of your samples. $\endgroup$ – DKNguyen Apr 17 at 1:57
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The answer posted earlier is a good one. Just for fun, here's an alternative view.

In the real world, the cosmological constant is positive. According to ref 1, this probably implies that the Hilbert space of the universe (if that's a valid application of quantum theory) must be finite-dimensional. And as emphasized in ref 2, in a finite-dimensional Hilbert space, strictly permenent records are impossible -- except that even after they're lost, they'll be (approximately) reconstituted by the same process that created them originally, over and over again.

That line of reasoning involves some pretty hefty extrapolations, but so would any other answer to this question.

(Hopefully nobody thinks I'm promoting this as the "correct" answer. Presuming to know the correct answer to a question like this would clearly be absurd. It's an academic question whose value is to inspire careful thought about the foundations of physics. That's where the papers I cited are coming from, and that's where this answer is coming from.)


References:

  1. Witten, "Quantum Gravity In De Sitter Space" (https://arxiv.org/abs/hep-th/0106109)

  2. Banks, Fischler, and Paban, "Recurrent Nightmares?: Measurement Theory in de Sitter Space" (https://arxiv.org/abs/hep-th/0210160)

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There is no way of recording information forever simply because there is no guarantee that anything will last forever. And if information is to last forever it must be recorded on some substrate that is guaranteed to last forever.

What we can ask for is for information to be reliably recorded for a certain length of time, whether this time is 100 years, 1000 years or 10,000 years.

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