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Show HN: Play with real quantum physics in your browser

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Re: Show HN: Play with real quantum physics in your browser

#31

Post by somenameforme »

Exuma wrote: post #18
ziofill wrote: post #15

Tangent, but interesting: how do you get fair samples from a biased coin? 1. You take a string of biased samples like 001011100101 2. you split it in pairs 00 10 11 10 01 01 3. you keep only pairs with a zero and a one in them 10 10 01 01 4. You assign 0 and 1 to them, e.g. 1 1 0 0, this is a fair sampling from an unbiased coin Why does it work? Because even if p(0) ≠ p(1), p(01) = p(10).

Damn, that is cool

Yeah this is probably the neatest little 5 second math thing I've ever seen. Can't believe I hadn't seen this before.

Re: Show HN: Play with real quantum physics in your browser

#33

Post by SaberTail »

Traubenfuchs wrote: post #13

My observation is too weak, the coins keep spinning. Maybe I am so disconnected from the rest of reality, I count as absolute, non destructive observer?

You're now entangled with the system, and so we will need someone else to observe you.

Re: Show HN: Play with real quantum physics in your browser

#34

Post by soulofmischief »

somenameforme wrote: post #31
Exuma wrote: post #18

Earlier quoted context omitted.

Damn, that is cool

Yeah this is probably the neatest little 5 second math thing I've ever seen. Can't believe I hadn't seen this before.

John von Neumann strikes again!

Wikipedia: https://en.wikipedia.org/wiki/Fair_coin#Fair_results_from_a_...

Original paper: https://mcnp.lanl.gov/pdf_files/InBook_Computing_1961_Neuman...

Re: Show HN: Play with real quantum physics in your browser

#35

Post by mattvr »

HelloUsername wrote: post #28
isotropy wrote: post #3

Earlier quoted context omitted.

Empirically, human-flipped coins have about a 1% bias toward the same side they started on: https://www.ams.org/publicoutreach/math-history/hap7-fifty-o...

But why it says "favors heads ~51%"

Updated to "favors one side 51%".

Re: Show HN: Play with real quantum physics in your browser

#36

Post by nineplay »

Question from someone who's not going to even pretend to understand quantum physics..

The explanation says the visualization shows the coin in all possible states. I'm trying to count quickly and it seems like about 8. Does all possible states mean there's an infinite number and 8 are shown for visualization purposes, or is there a finite predictable number of possible states.

Re: Show HN: Play with real quantum physics in your browser

#38

Post by Rooster61 »

HelloUsername wrote: post #28
isotropy wrote: post #3

Earlier quoted context omitted.

Empirically, human-flipped coins have about a 1% bias toward the same side they started on: https://www.ams.org/publicoutreach/math-history/hap7-fifty-o...

But why it says "favors heads ~51%"

What sort of uncivilized mook dares flip a coin with tails facing up? Preposterous

Re: Show HN: Play with real quantum physics in your browser

#40

Post by shalg »

nineplay wrote: post #36

Question from someone who's not going to even pretend to understand quantum physics.. The explanation says the visualization shows the coin in all possible states. I'm trying to count quickly and it seems like about 8. Does all possible states mean there's an infinite number and 8 are shown for visualization purposes, or is there a finite predictable number of possible states.

Quantum mechanics tells us that the qubit (coin) can exist in any linear superposition of heads and tails. To express this you write a|heads> + b|tails> the only constraint is that a^2 + b^2 must equal 1. Now why would that be the constraint? It is because a^2 and b^2 are the probabilities of measuring heads and tails respectively.

In this example the coin is put into the state where an and b equal 1/sqrt(2) to give an equal probability of each outcome. So there is exactly one state associated with the coin. Now this state does lead to two possible outcomes but the underlying state (that can not be directly observed) is exactly one thing.

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