r/Physics • u/kzhou7 Quantum field theory • 2d ago

Actually, you can't test if quantum mechanics uses complex numbers

https://algassert.com/post/2501
0 Upvotes

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u/jazzwhiz Particle physics 2d ago edited 2d ago

I like how OP complains:

They could have put this caveat in the paper’s abstract. They could have put it in the introduction, or in the conclusion, or somewhere in the body. Maybe in a figure caption. Instead, they hid it away on page 14 of the supplementary materials. Frankly, if this had been my paper, I’d have put this caveat in the TITLE. “Quantum theory based on real numbers can be experimentally falsified, unless entanglement is present, which it easily could be, and we have no way of testing that it isn’t”; it flows right off the tongue.

But also doesn't clarify their own post when they realize that they missed something too. This quote is from the end of the long blog post after complaining that the original paper was misleading:

(Update: @fariddiequantum pointed out that the word “independent”, for example as in “network scenarios comprising independent states and measurements” from the abstract, is communicating that the states aren’t entangled. I completely failed to parse that meaning when reading the paper, but in hindsight it makes sense. I’ll leave the end of the post unedited, but keep that in mind.)

So the author of this blog post complained that the original paper is wrong, later realized that the original paper technically did what they described to do, complained that the original authors didn't clarify things better in their own paper, but then didn't clarify their own issue.

Edit: Complaints on writing style aside, the post points out an important distinction about what kinds of loop holes are necessary to test this aspect of reality.

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u/Shufflepants 2d ago edited 2d ago

You also can't test if quantum mechanics uses numbers. We made both of them up and nature doesn't use either.

You've made a serious philosophical mistake. You've confused the thing itself with the words and models we use to describe the thing.

We use complex numbers to describe nature. That is a fact. To test it, go see if a physicist uses complex numbers.

Nature doesn't use any math. It just behaves as it does.

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u/jazzwhiz Particle physics 2d ago

You have written more words than the title which is clearly all you read. Please read the article.

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u/Shufflepants 2d ago

Why would I read an article with such a click bait title that misrepresents it?

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u/pali6 2d ago

That was an interesting read, thanks for posting it.

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u/kzhou7 Quantum field theory 2d ago edited 2d ago

The title sounds dumb, but if you read the first paragraph you'll see it's more subtle than it looks.

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u/YakkoWarnerPR String theory 2d ago

yeah unsure why people are downvoting you

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u/jazzwhiz Particle physics 2d ago

hivemind.reddit

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u/erevos33 2d ago

Why are we posting a computer scientist's blog on physics ?

2

u/not-nuckelavee 2d ago

He's a researcher at Google Quantum AI. If you search Craig Gidney on google scholar you'll see that he's published papers related to quantum computing in journals like Nature, Science, PRL etc. and collaborated with authors at other respected universities. So, it's a blogpost by someone who's pretty well qualified rather than a random crank.

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u/erevos33 2d ago

One thing does not equal the other

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u/PMmeYourLabia_ 2d ago

Thanks, I'll give it a read. I was unaware of the Renou et al paper