The Paradox of Laplace's Demon
For my blog choice #3 I choose to write about The Paradox of Laplace's Demon. This paradox talks about Laplace postulates a super-intelligence that could know the positions, velocities, and forces on all the particles in the universe at one time, and thus know the universe for all times. Laplace is a french mathematician who devised his own imaginary demon half a century before Maxwell proposed his. Laplace's demon is pretty much a super computer. Laplace's demon is so much more powerful than Maxwells. This demon is so smart it can tell the exact position and state of motion not only of every air molecule in a box, but of every particle in the Universe, and fully understands the law of physics that describes how they interact with each other. That means that a know it all demon could work out how the Universe will evolve over time and be able to predict its state in the future.
An good example of this demon is a super computer like I mentioned above. This computer is so powerful and has so much memory that it can know every tiny detail about the Universe, right down to the state of all the atoms that make up the computer itself and every electron flowing through its circuitry. With all that information it can compute how the future will unfold very precisely. This computer receives simple instructions by its operators, which it predicts it would receive, to self-destruct if it computes a future in which it no longer exists, but to do nothing if it computes a future in which it no longer exists. If it predicts a future in which it is still around, then it won't be, and if it predicts a future in which it is not then it will be. Either way, its prediction is wrong. The real question is will it survive or not.
Laplace wasn't looking for a paradox, he was trying to highlight something widely believed to be incontestable at the time that the Universe is deterministic. This chapter revolves around the word deterministic. Determinism means that the future can be predicted. However, the above paradox suggests that we must rule out this possibility: that Laplace was wrong and our universe cannot be deterministic. But, as we will see, subject to certain caveats and uncertainties in our current physical theories, we have every reason to believe that our universe is indeed deterministic.
A specific way of ruling out time-travel paradoxes is to insist that time travel to the past is simple impossible. But in Laplace's demons case, no time time travel is necessary; the demon cannot escape the future, which is heading its way even if it does nothing. And that's where we need another explantation to resolve the paradox. The simplest option is often the correct one, and here it must surely be that, unlike the past, which is fixed, the future is still open and yet to be determined. What the demon can presumably see is just one possible future. Surely, in order for it and for us to be able to make free choices, our universe cannot be deterministic. It's an appealing argument, but not necessarily the one needed to resolve the Paradox of Laplace's Demon.
The problem is that if the computer really can predict one of a potentially infinite number of possible futures, which just happened to be the one in which this profound scientific discovery is made, then we can see that there is no element of real prediction at all there: it is no different from its having hit upon the idea through sheer chance. It is somewhat similar to the popular "infinite monkey theorem" in which a monkey hitting randomly on a typewriter for an infinite length of time will at some point, by sheer accident, type out the complete works of shakespeare. We have therefor learned nothing from this explanation. And while it is not impossible that the computer could come up with a new scientific "theory of everything" by accident like this, that outcome is so impossible that we can ignore it. The computer will have started its calculation from the present moment and taken into account the current state of knowledge and the trains of thought of the worlds leading theoretical physicists, as well as the ideas for new experiments that could be carried out in the future, so it is somewhat less improbable than a monkey tapping away randomly at a keyboard coming up with the same theory-but the chance of that outcome emerging is still vanishingly small.
So pretty much this chapter talks about Laplace's Demon that knows the future, but doesn't require time travel, it just awaits for the future to come to it, and while waiting it can meddle with the present to force a different future to evolve.
Work Cited:
"Laplace's Demon." Laplace's Demon. Carlo Cercignani, n.d. Web. 02 Nov. 2014.
"Laplace's Demon." Gdels Lost Letter and PNP. Rjlipton, n.d. Web. 03 Nov. 2014.
Al-Khalili, Jim. "The Paradox of Laplace's Demon." Paradox: The Nine Greatest Enigmas in Physics. New York: Broadway, 2012. N. pag. Print.
The paradox you presented at the end of the 2nd paragraph still alludes me. Why would the computer not be in the future if it predicts it will be? And why would it do nothing if it no longer exists? However, this was an interesting concept to think about. A being and machine that can predict anything is something out of science-fiction. The infinite monkey theorem also sounded cool. A monkey, out of random chance, that could type a shakespeare play sounds crazy, but it just opens up questions on what can happen at random if things like that could happen.
ReplyDeleteIt was interesting to read about your example of the computer that could predict how the future will unfold because of all the memory that it holds. Although the computer can't time travel, I thought that it could be really amazing if it was able to. Still, Laplace being deterministic was something very interesting to read about and makes me think that somewhere out there, somebody or something is able to see or unfold the future just like Laplace's Demon states.
ReplyDeleteThe thought of a "computer" being able to process every single outcome of the future is mind boggling to me. The amount of power a computer would need to do that is unfathomable. Laplace was a very radical thinker by calling the universe deterministic. Laplace, living in the 18th and 19th century, was also a visionary in some sorts. Not many men were thinking like he was. Everyone during this time just kind of accepted the universe as this giant mystery. Men like Laplace are the people who changed the thinking of many scientists. Great summary!
ReplyDeleteI have never heard of Laplace before so I found this paradox interesting. I feel like Laplace was very imaginative. I liked to read about the computer and all the computing powers that it could have. The monkey also interested me. It would be crazy if a monkey could even write, let alone a whole Shakespeare play! I really liked your summary!
ReplyDeleteThis paradox was confusing at times for me, but the example of the super computer helped me understand it. It would be impossible for such a thing as a super computer to exist as it contradicts itself based on how it predicts its own future. That amount of power in that would be astonishing because it can see everything in the future based on that great amount of intelligence it would have.
ReplyDeleteI truly agree with what Charlie said about this summary. Knowing a computer can predict everything that will happen in the future is not only mind boggling, but it's also kind of scary. It makes you truly wonder when the line on technology will be drawn. From reading this it seems like that line will never be drawn. Don't get me wrong I believe the improving technology is great for a society, but there also needs to be a line drawn. A computer knowing everything is getting pretty close to that line.
ReplyDeleteThis concept was quite hard to comprehend. This paradox seemed very unrealistic since a lot of essential components seemed a bit imaginary. I just couldn't understand this paradox.
ReplyDelete"For my blog choice #3 I choose to write about The Paradox of Laplace's Demon." first off, thank you for clarifying. secondly, i found this concept to be extremely hard to understand, not because i lack the mental aptitude to do so, but it is due to the fact that paragraphs 1&2 and Paragraphs 3&4 are the exact same thing just worded differently providing no progress on the concept. I went ahead on my own and did some research on the topic and found it to my liking. Piece of advice would be to check your grammar and conventions more so that it is an easier read.
ReplyDeleteI must say that I didn't quite understand the paradox but the concept of determinism interested me. Our lives depend on predictions everyday; in weather forecasts, markets, in Science researches etc. It is undeniable that there are lots of uncontrolled variables when making predictions, leave alone the fact that the humans do not possess knowledge of everything in the universe, yet they try to determine its fate;and technology that just facilitates this process
ReplyDeleteI've never heard of this before and it was a little hard to comprehend. Except the monkey part really grabbed my attention about how one monkey could wrote a shakespeare play! That was cool to read about.
ReplyDeleteThe infinite monkey theorem has always been an interesting one to me. Just think of the probability of the exact position of every letter, punctuation, space, etc occurring just at random. It's so crazy to wrap your head around. As for Laplace's demon, you can think of it kind of like the paradox "new mission: deny this mission" The mission is to deny the mission, however, by denying the mission, you're actually accepting it.
ReplyDeleteI also looked up more information on Laplace's demon to put the pieces together. I found that because the location and exact velocities are known, the past and future values of a time are still considered to be entitled. I found it interesting that if it was vast enough, nothing will be uncertain. Interesting topic.
ReplyDeleteI liked your topic. I found it to be interesting with the paradox and determinism. I also liked how you explained the infinite monkey theorem.
ReplyDeleteThe paradox that you presented in this blog post is truly mind boggling. It is hard to comprehend at first, and not at all because of the way that you explained it, it is simply that paradoxes take a little while to understand. If time is taken, then the paradox can be understood, and you explain it very well. I am really intrigued by paradoxes, and this one did not fail to intrigue me. I really liked the way that you worked into the explanation of the paradox by first giving the history of it and how it came to be.
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