Wednesday, August 21, 2019

Carroll writes new book on Many Worlds

Peter Woit asks What’s the difference between Copenhagen and Everett?
What strikes me when thinking about these two supposedly very different points of view on quantum mechanics is that I’m having trouble seeing why they are actually any different at all.
To the extent that they are just interpretations, there is no substantive difference. With disputes about the definitions, this is not so clear.

Here are a couple of the better comments:
They difference is in the part that you don’t want to discuss, which is that Everettians postulate the other worlds are real, while Copenhagenists refuses to say anything about what cannot be observed.

Good old books inform that the same issue had been fiercely debated around 1926, when Schroedinger/Einstein wanted to describe everything via a deterministic local equation, getting rid of quantum jumps. Heisenberg/Bohr explained that it’s not possible because we see particles as events. Decoherence and all modern stuff allow to understand better but don’t change the key point: we need probabilities. So the Schroedinger equation is just a tool for computing probabilities in configuration space.
Woit goes on to review Sean M. Carroll's new book, which is a 368-page argument for the Many World Theory of quantum behavior.

Woit says Carroll is a good writer and explainer, but the Many Worlds stuff is the babbling of a crackpot. They theory is so silly it is hard to take anyone seriously who pushes Many Worlds.

Thursday, August 15, 2019

The Quantum Computing Party may never start

SciAm reports:
The Quantum Computing Party Hasn’t Even Started Yet

But your company may already be too late ...

For example, at IonQ, the company I co-founded to build quantum computer hardware, we used our first-generation machine to simulate a key measure of the energy of a water molecule. Why get excited when ordinary computers can handle the same calculation without breaking a sweat? ...

If you pay even a little attention to technology news, you've undoubtedly heard about the amazing potential of quantum computers, which exploit the unusual physics of the smallest particles in the universe. While many have heard the buzz surrounding quantum computing, most don't understand that you can't actually buy a quantum computer today, and the ones that do exist can't yet do more than your average laptop. ...

It will take a few more years of engineering for us to build capacity in the hundreds of qubits, but I am confident we will, and that those computers will deliver on the amazing potential of quantum technology.

The choice facing technology leaders in many industries is whether to start working today on the quantum software that will use the next generation of computers or whether to wait and watch the breakthroughs be made by more agile competitors.
Or wait to watch all the quantum computer companies fail.

He is right that you cannot buy a quantum computer, and the research models are so primitive as to be useless.

The party may never start.

Tuesday, August 13, 2019

Quantum Cryptography is still useless

IEEE Spectrum reports:
Quantum Cryptography Needs a Reboot

Quantum technologies—including quantum computing, ultra-sensitive quantum detectors, and quantum random number generators—are at the vanguard of many engineering fields today. Yet one of the earliest quantum applications, which dates back to the 1980s, still appears very far indeed from any kind of widespread, commercial rollout.

Despite decades of research, there’s no viable roadmap for how to scale quantum cryptography to secure real-world data and communications for the masses.

That’s not to say that quantum cryptography lacks commercial applications. ...

From a practical standpoint, then, it doesn’t appear that quantum cryptography will be anything more than a physically elaborate and costly—and, for many applications, largely ignorable—method of securely delivering cryptographic keys anytime soon.
So it does lack commercial applications. The technology does not do anything useful, as I have explained here many times.
“The same technologies that will allow you to do [quantum crypto] will also allow you to build networked quantum computers,” Bassett says. “Or allow you to have modular quantum computers that have different small quantum processors that all talk to each other. The way they talk to each other is through a quantum network, and that uses the same hardware that a quantum cryptography system would use.”

So ironically, the innards of quantum “cryptography” may one day help string smaller quantum computers together to make the kind of large-scale quantum information processor that could defeat… you guessed it… classical cryptography.
So all these folks think that classical cryptography is doomed. Someone will first have to invent a quantum processor, because we can try to network such processors.

Friday, August 9, 2019

$3M prize for dead-end physics idea

Dr. Bee reports:
The Breakthrough Prize is an initiative founded by billionaire Yuri Milner, now funded by a group of rich people which includes, next to Milner himself, Sergey Brin, Anne Wojcicki, and Mark Zuckerberg. The Prize is awarded in three different categories, Mathematics, Fundamental Physics, and Life Sciences. Today, a Special Breakthrough Prize in Fundamental Physics has been awarded to Sergio Ferrara, Dan Freedman, and Peter van Nieuwenhuizen for the invention of supergravity in 1976. The Prize of 3 million US$ will be split among the winners.
What you never heard of this work? That is because it was a dead-end, and never led to anything.

For a couple of years in the 1970s, supersymmetry gravity was an exciting idea, because it was thought that it would make quantum gravity renormalizable. However that turned out to be false, and the theory is worthless.

Like string theory, it has no connection to any observational science. But even work, it doesn't even make sense as a physical theory.

Update: Lumo writes:
Nature, Prospect Magazine, and Physics World wrote something completely different. The relevant pages of these media have been hijacked by vitriolic, one-dimensional, repetitive, scientifically clueless, deceitful, and self-serving anti-science activists and they tried to sling as much mud on theoretical physics as possible – which seems to be the primary job description of many of these writers and the society seems to enthusiastically fund this harmful parasitism.
Check them yourself. The Nature article says:
A lack of evidence should also not detract from supergravity’s achievements, argues Strominger, because the theory has already been used to solve mysteries about gravity. For instance, general relativity apparently allows particles to have negative masses and energies, in theory.
No, that is a big lie. Supergravity has nothing to do with positive mass. For details, see the comments on Woit's blog. Briefly, Witten published an outline for a proposed spinor proof of the Schoen-Yau positive mass theorem, and the paper ended with a short section starting with "a few speculative remarks will be made about the not altogether clear relation between the previous argument and supergravity." That's all.

Friday, August 2, 2019

Science journals must be politically correct

Indian-born British writer Angela Saini has found the formula, with articles in Scientific American:
The “race realists,” as they call themselves online, join the growing ranks of climate change deniers, anti-vaxxers and flat-earthers in insisting that science is under the yoke of some grand master plan designed to pull the wool over everyone’s eyes. In their case, a left-wing plot to promote racial equality when, as far as they’re concerned, racial equality is impossible for biological reasons. ...

Populism, ethnic nationalism and neo-Nazism are on the rise worldwide. If we are to prevent the mistakes of the past from happening again, we need to be more vigilant.
And Nature:
Racist ‘science’ must be seen for what it is: a way of rationalizing long-standing prejudices, to prop up a particular vision of society as racists would like it to be. It is about power. ... A world in thrall to far-right politics and ethnic nationalism demands vigilance. We must guard science against abuse and reinforce the essential unity of the human species.
She argues that there is no such thing as human races, and that genetics has nothing to do with the observed differences in athletic performance.

She is from India, which is not really competitive in the sports the rest of the world. So perhaps she does not realize how obvious the biological differences in sports are. But what excuse does Nature and SciAm for publishing her nonsense?

If these journals can lie to us about human races, then they can also lie about climate change and a lot of other subjects.