Creating the First Quantum Internet
Here is the misguided attempt at quantum crypto:
Scientists in Chicago are trying to create the embryo of the first quantum internet. If they succeed, the researchers will produce one, 30-mile piece of a far more secure communications system with the power of fast quantum computing. From a report:
The key was the realization of an unused, 30-mile-long fiber optic link connecting three Chicago-area research institutions -- Argonne National Lab, Fermi Lab and the University of Chicago. This led to the idea to combine efforts and use the link for what they call the Chicago Quantum Exchange. David Awschalom, an Argonne scientist and University of Chicago professor who is the project's principal investigator, tells Axios that the concept is difficult to grasp, even for experts.
MIT Technology Review elaborates:
The QKD approach used by Quantum Xchange works by sending an encoded message in classical bits while the keys to decode it are sent in the form of quantum bits, or qubits. These are typically photons, which travel easily along fiber-optic cables. The beauty of this approach is that any attempt to snoop on a qubit immediately destroys its delicate quantum state, wiping out the information it carries and leaving a telltale sign of an intrusion. The initial leg of the network, linking New York City to New Jersey, will allow banks and other businesses to ship information between offices in Manhattan and data centers and other locations outside the city.
However, sending quantum keys over long distances requires "trusted nodes," which are similar to repeaters that boost signals in a standard data cable. Quantum Xchange says it will have 13 of these along its full network. At nodes, keys are decrypted into classical bits and then returned to a quantum state for onward transmission. In theory, a hacker could steal them while they are briefly vulnerable.
This is really foolish. We have cheap reliable end-to-end encryption that has not been broken.
The quantum crypto methods are unable to offer similar assurances. They cannot authenticate messages. They cannot do end-to-end encryption, so they require trusted nodes. They are subject to hardware faults, and such faults have been used to break all the commercial equipment.
The big advantage of the quantum crypto is that you are supposed to be able to shut down the network if you detect a probability of an attack. Who wants that? The whole point of the real internet is to always transmit traffic, regardless of problems. The quantum internet will shut down at the first sign of a problem.
The whole idea of a quantum internet is a scam.
Posted by Roger at 8:00 AM 1 comment: Links to this post
Labels: quantum
Stop doing fundamental physics
Lubos Motl writes:
The video starts boldly:
I will talk about string theory not because I think it's interesting but because it's uninteresting and we should stop talking about it.
Holy cow. String theory remains the only game in town and everyone who wants to scientifically investigate any physical phenomena that go beyond effective quantum field theories – whose limitations are self-evident and well-known – simply must learn string/M-theory. There is no known alternative. To "stop talking about it" is almost exactly equivalent to stop doing fundamental physics. ...
On the other hand, Hossenfelder clearly doesn't have any alternative to string theory. She doesn't have any quantum mechanical theory that agrees with Einstein's equations at long distances but preserves the information when the black hole evaporates. But she – and her brain-dead followers – just don't care.
Yeah, I just don't care about such a theory.
Einstein's equations at long distances are the same as for Newtonian gravity. Either way, you can add dark energy, altho, as Bee explains, much of string theory was based on dark energy being negative, and we now know that it is positive.
But string theory preserves the info when a black hole evaporates? That is just nonsense. It makes more sense to talk about the Biblical apocalypse.
Maybe fundamental physics should stop. It is going nowhere. All that brainpower could be put to more productive purposes.
Posted by Roger at 8:00 AM 3 comments: Links to this post
Labels: strings
Krauss pushed into retirement
I posted before about physicist Lawrence Krauss being silenced.
BuzzFeed brags that it has hounded a physicist out of academia:
Lawrence Krauss, the celebrity physicist who faced dismissal from Arizona State University for violating sexual misconduct policy, has agreed to step down from the school.
In statements posted on Facebook and Twitter on Sunday, Krauss said: "I have chosen to retire from ASU in May, 2019, when I turn 65."
I am not going to pile on here. I believe he is innocent until proven guilty. Among the accusations are that he made "sexist comments".
Krauss has written some worthwhile popular physics books. If I were going to be offended by his comments, then I would probably be offended by his leftist political views. Making sexist comments is not a crime. Not yet.
Explaining the failure of Many-Worlds
Philip Ball explains what is wrong with the Many Worlds Interpretation of quantum mechanics:
The MWI is qualitatively different from the other interpretations of quantum mechanics, although that's rarely recognized or admitted. For the interpretation speaks not just to quantum mechanics itself but to what we consider knowledge and understanding to mean in science. It asks us what sort of theory, in the end, we will demand or accept as a claim to know the world. ...
What the MWI really denies is the existence of facts at all. It replaces them with an experience of pseudo-facts (we think that this happened, even though that happened too). In so doing, it eliminates any coherent notion of what we can experience, or have experienced, or are experiencing right now. We might reasonably wonder if there is any value — any meaning — in what remains, and whether the sacrifice has been worth it. ...
It says that our unique experience as individuals is not simply a bit imperfect, a bit unreliable and fuzzy, but is a complete illusion. If we really pursue that idea, rather than pretending that it gives us quantum siblings, we find ourselves unable to say anything about anything that can be considered a meaningful truth. We are not just suspended in language; we have denied language any agency. The MWI — if taken seriously — is unthinkable. ...
What quantum theory seems to insist is that at the fundamental level the world cannot supply clear "yes/no" empirical answers to all the questions that seem at face value as though they should have one. The calm acceptance of that fact by the Copenhagen interpretation seems to some, and with good reason, to be far too unsatisfactory and complacent. The MWI is an exuberant attempt to rescue the "yes/no" by admitting both of them at once. But in the end, if you say everything is true, you have said nothing.
That's right. Ultimately MWI says nothing that you would want from a scientific theory. There are no facts, predictions, or confirming experiments.
MWI just says that everything that can happen does happen in some parallel world. It allows you to think and believe whatever you want. Probabilities are meaningless. Reality and facts are meaningless.
MWI is just the same as the child's fantasy. The proponents give the impression that it is a scientific theory that gives a detailed explanation of the worlds, with Hilbert space, wave function, Schroedinger equation, atomic forces, etc. Yes, but none of them can explain how all that apparatus tells you anything beyond the simplistic child's fantasy. There are no predictions or confirming experiments.
I used to to think that string theory was the epitome of unscientific thinking. But string theory is vastly more reasonable that MWI. String theory at least had some hope of getting some theoretical explanations. MWI explains nothing, and discards almost everything we know about science.
Update: LuMo writes:
Now, Ball has written a text about some conceptual and basically insurmountable problems of the "many-world interpretation" paradigm sometimes used to misinterpret quantum mechanics. Among other things, he focused on the impossibility to define what a "splitting of the Universes" is and when and how many times it takes place. This is of course one of the problems about MWI that I see and often write about – but there are others, too. ...
However, the comment sections are frustrating. Both articles have attracted over 100 comments by now. Pretty much all the most upvoted comments attack Wolchover's and Ball's texts. You can see that none of these people actually understands quantum mechanics and all of them assume that classical physics is right throughout their comments and lives.
I had not noticed that Quanta mag allows comments, because my adblocker blocks them.
I would not bother criticizing MWI, except that it has such a huge following, from leading physicists on down to the general public. Here is one of the dopey comments:
The fact is that the MWI is strictly adherent to the mathematics of quantum physics. There is no extra phenomenon like "observation" (that's just entanglement) there is no extra phenomenon like "waveform collapse" the entangled particle becomes part of a more complex waveform.
MWI doesn't have to justify adding any additional complexity to QM because it doesn't. Copenhagen, Pilot Wave, et. al. are the interpretations that add extra complexity that don't show up in the math, so they're the ones that have to justify that complexity. What the hell is an observer? What the hell is waveform collapse?
MWI doesn't have to define observers because it does not make any predictions.
The math of quantum physics makes predictions that are verified by experiments. MWI makes no such predictions. Therefore MWI does not adhere to the math of quantum physics.
The decline of relativistic mass
Vesselin Petkov notes how the concept of "relativistic mass" has gone out of fashion:
These facts make the campaign against the concept of relativistic mass both inexplicable and worrisome. Instead of initiating and stimulating research on the origin of relativistic mass (and on the nature of mass in general) in order to achieve a more profound understanding of this fundamental concept in physics,7 the relativistic mass is not mentioned at all in many publications8 (see, for example, the well-known textbook [35]) or, if it is mentioned, it is done to caution the readers9, that "Most physicists prefer to consider the mass of a particle as fixed" [25, p. 760], that "Most physicists prefer to keep the concept of mass as an invariant, intrinsic property of an object" [32], that "We choose not to use relativistic mass, because it can be a misleading concept" [36] or to warn them [22, p. 1215]:
Watch Out for "Relativistic Mass"
Some older treatments of relativity maintained the conservation of momentum principle at high speeds by using a model in which a particle's mass increases with speed. You might still encounter this notion of "relativistic mass" in your outside reading, especially in older books. Be aware that this notion is no longer widely accepted; today, mass is considered as invariant, independent of speed. The mass of an object in all frames is considered to be the mass as measured by an observer at rest with respect to the object.
As he explains, this opinion is pretty arbitrary, and relativistic mass is analogous to length contraction or time dilation. Yes, it depends on the frame, and it can be a little confusing, but that's relativity.
Posted by Roger at 8:00 AM No comments: Links to this post
Labels: relativity
Biologist defends de-publishing papers
Computational biology professor Lior Pachter writes:
In the case discussed in this blog post, the underlying subtext is pervasive sexism and misogyny in the mathematics profession, and if this sham paper on the variance hypothesis had gotten the stamp of approval of a journal as respected as NYJM, real harm to women in mathematics and women who in the future may have chosen to study mathematics could have been done. It's no different than the case of Andrew Wakefield's paper in The Lancet implying a link between vaccinations and autism. By the time of the retraction (twelve years after publication of the article, in 2010), the paper had significantly damaged public health, and even today its effects, namely death as a result of reduced vaccination, continue to be felt.
He and his liberal colleagues have a funny idea of what science is all about.
Wakefield's paper did not damage public health. It merely suggested a health concern, based on some very limited data. The proper response would have been to do a more thorough study on measles vaccine safety.
Instead the medical authorities blamed Wakefield for reduced confidence in vaccination, so they retracted the paper and stripped Wakefield of his medical license.
Those who suspected a cover-up of vaccine risks had their suspicions confirmed. Nobody would every publish anything critical of vaccines again, or risk losing his medical license.
Pachter points out that papers on the evolution of sex differences go back to 1895, at least. So how is it that publishing another one will do real harm to women in mathematics? Pachter doesn't actually explain what is wrong with the paper, except that it is politically incorrect and fails to cite some previous work on the subject.
I do not get confidence in vaccines by having a ban on papers describing vaccine dangers. And I do not think that women should get encouragement in math by banning papers on variance in mathematical ability.
Labels: math, science
Claiming quantum mechanics is inconsistent
These is whole industry of physicists working in quantum foundations who make various arguments that quantum mechanics doesn't make any sense. They can't deny that quantum mechanics correctly predicts experiments, and yet they keep coming up with clever sleight-of-hand thought experiments and paradoxes that supposedly show that the theory does not work.
The whole enterprise is foolish. If there were really such contradictions, then there would be some failure to predict experiments.
Scott Aaronson pauses from his agony of being a Jewish leftist Trump-hating professor in a red state to explain:
So: a bunch of people asked for my reaction to the new Nature Communications paper by Daniela Frauchiger and Renato Renner, provocatively titled "Quantum theory cannot consistently describe the use of itself." Here's the abstract:
Quantum theory provides an extremely accurate description of fundamental processes in physics. It thus seems likely that the theory is applicable beyond the, mostly microscopic, domain in which it has been tested experimentally. Here, we propose a Gedankenexperiment to investigate the question whether quantum theory can, in principle, have universal validity. The idea is that, if the answer was yes, it must be possible to employ quantum theory to model complex systems that include agents who are themselves using quantum theory. Analysing the experiment under this presumption, we find that one agent, upon observing a particular measurement outcome, must conclude that another agent has predicted the opposite outcome with certainty. The agents' conclusions, although all derived within quantum theory, are thus inconsistent. This indicates that quantum theory cannot be extrapolated to complex systems, at least not in a straightforward manner.
The paper authors separately argue that this proves the many-world interpretation.
That conclusion should be enuf to dispose of the argument. The MWI does not predict any experimental outcomes. There is nothing scientific about it. It is like some solipsist saying anything can happen in his imagination.
Aaronson explains the errors in more detail. So does Lubos Motl. Somehow this paper got published in a Nature journal. It has become respectable to trash quantum mechanics with silly arguments.
Fundamental physics is over
About the recent Nobel physics prize, someone commented:
that's not even applied science, that's technology
People do not get that fundamental physics is over (you would not call seriously "string theory" "scientific" would you?).
I know I am repeating what Lord Kelvin said to his embarrassment just before great discoveries in relativistic physics, quantum physics, etc.
Nevertheless, that's truth: everything ends, everything has limits, humanity has limits and science has limits.
The clear indication that we are close to the limit is absence of ANY fundamental discoveries since a long time ago.
We are gradually shifting towards applied science and mere technology. All of three fields, basic science, applied science and technology are essential for humanity, but the fact is that the first one is almost over or probably over already.
Call them for what they are: Nobel Prizes in Technology
I mostly agree with this.
Future historians will look back at the XX century and say that is when the fundamental problems of science got sorted out.
Sure, there are a few things that seem only partially understood, and that a better understanding seems likely or possible. But for many of those things, it is possible that they will never be better understood than they are today.
What do we have to show for this century? Faster lasers. Gravity wave detection. Higgs boson detection. Better telescopes. Etc. But we haven't had any significant advances in fundamental physics in about 40 years.
Physics was invented and built by men
A reader sends this BBC story:
A senior scientist who said physics "was invented and built by men" has been suspended with immediate effect from working with the European nuclear research centre Cern.
Prof Alessandro Strumia, of Pisa University, made the comments during a presentation organised by the group.
He said, in comments first reported by the BBC's Pallab Ghosh, that physics was "becoming sexist against men".
Cern said on Monday it was suspending Prof Strumia pending an investigation.
It stated that his presentation was "unacceptable".
LuMo compares this to persecuting Galileo here and here.
No woman would be fired for pushing the accomplishments of women or for whining about men. This man was fired for presenting some facts and opinions about men. So his firing proved his point -- physics is sexist against men.
I thought that his punishment was potentially justifiable because he was injecting political opinions into a scientific context. But his talk was to a gender politics workshop where all the other opinions complained about male oppression. They will never get to the truth as long as contrary views are censored.
The Galileo analogy is a little silly. Galileo was allowed to publish his arguments about the Earth going around the Sun. He got into trouble when said the official Bible interpretations had been proven wrong.
I am writing this as the Nobel Physics prizes are announced. Marie Curie got one about a century ago. I don't think that there have been any women since. As usual, three more men got the prize this year.
One of the three prizewinners was a woman, the first in 55 years.