Thursday, October 11, 2018

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.

Wednesday, October 10, 2018

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.

Sunday, October 7, 2018

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.

Friday, October 5, 2018

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.

Tuesday, October 2, 2018

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.