What do you think of this possibility, Avsim quantum computer experts.

Are, as Brian suggests as a possibility, quantum computers doing things that classical computers can't because they are calculating in multiple universes?

 

 

Whenever I hear about stuff like this (and I include quantum mechanics in my thought process), it makes me wonder if we really have any clue at all about the true nature of reality.

Martin!

Don't! pull! my! strings!

The many-worlds interpretation is one way of interpreting quantum physics, but decoherence theory works better for all practical purposes. So, from my perspective, quantum computers do not work in a multiverse, they just exploit some oddities in quantum correlations, which admittedly are not easy to explain. But that doesn't mean we need infinitely many universes to explain it.

There you have it. Another 10 minutes off beta testing something really cool 🙂

Peter

But Peter, maybe, just maybe...  😁 I'm playing devils advocate, of course... 

I recall you aren't a fan of MWI, in general?

 

Quote

Scientists like David Deutsch and Hartmut Neven suggest quantum computers may operate in multiple universes, based on the Many-Worlds Interpretation (MWI) of quantum mechanics. They propose that the power of quantum computation comes from a computer performing parallel computations across different realities, a concept that Deutsch has argued for since the 1980s and Neven recently linked to Google's quantum processor performance. Other scientists, however, remain skeptical and argue that other interpretations of quantum mechanics can explain quantum computing without invoking parallel universes

Scientists who support this view

• David Deutsch: A physicist and strong proponent of the Many-Worlds Interpretation (MWI), Deutsch argues that quantum computers provide evidence for parallel universes. He suggests that the speed of a quantum computer comes from it performing calculations in multiple universes simultaneously.
• Hartmut Neven: A researcher at Google, Neven has stated that the performance of Google's "Willow" quantum chip "lends credence to the notion that quantum computation occurs in many parallel universes," in line with Deutsch's predictions. He points to the speed of a specific computation that would take a classical supercomputer an impossibly long time.
• Max Tegmark and Sean Carroll: These scientists are also mentioned as supporters of the Many-Worlds Interpretation, though their specific connection to the quantum computer argument is less detailed in the provided snippets. 

 

 

 

 

 

 

Edited November 8, 2025Nov 8 by martin-w

Exactly: playing devil's advocate just to get me upset 😉

Yep, I am not a fan of the MWI, and I am not alone. I don't personally know any quantum physics expert who does, but I know quite a few cosmologists who like it a lot. The reason is that decoherence theory needs an environment that interacts with your quantum system, and that interaction elegantly explains a lot of the weirdness in quantum physics. But if you describe the universe as a whole, there isn't any environment left with which it could interact. So cosmologists need something else.

IMHO, the MWI doesn't pass Occam's razor. You need to invent infinitely many universes just to explain what is going on in our own. And one common description of Occam's principle says "Entities are not to be multiplied without necessity" 🙂

Is it really that easy to use Occam's Razor as a guiding principle in the weird world of quantum mechanics?

Six Seven !

2 hours ago, Christopher Low said:

Is it really that easy to use Occam's Razor as a guiding principle in the weird world of quantum mechanics?

Nice rebuttal 🙂
No, the razor is not a law, just a guideline anyway (who recognizes the movie? 😉)

And I would even grudgingly accept that the MWI is maybe the only consistent interpretation of quantum physics that applies to everything. But (a) that doesn't mean it is right (like flat Earth wasn't right 600 years ago), and (b) if you are content with a little less than everything (such as only out galaxy), then decoherence theory is perfectly fine and only requires one universe. You wouldn't postulate 6 different universes every time you roll a die, would you?

51 minutes ago, Fielder said:

Six Seven !

(|6>  +  |7>) /sqrt(2) 🙂