Why the foundations of physics have not progressed for 40 years • Hacker News Board

Re: Why the foundations of physics have not progressed for 40 years

#121

Post by ssivark » Mon, Jan 13, 2020, 4:52 PM UTC

ISL wrote: post #86

I strongly disagree that the foundations of physics have not progressed for 40 years. We have been looking really hard for answers to persistent questions. While we have not found affirmative answers, physicists have systematically ruled out option after option after option. We have not yet discovered a unified-theory-of-everything, but we know a whole lot more about what that theory is not . Furthermore, the past 40…

Love the Tao Te Ching quote!

To add to your point, scientists have been chasing inconsistencies exactly like Sabine said. They’re chasing dark matter, dark energy, quantum gravity, early universe cosmology, naturalness (arguable; more of a theoretical inconsistency), and quantum foundations (smaller effort).

So I don’t see the point of vague allusions to the philosophy of science. If anyone has a concrete proposal---inspired from philosophy or whatever else, doesn’t matter---the proposal will typically be treated on its merits. Modulo caveats about humans being humans and all that.

Re: Why the foundations of physics have not progressed for 40 years

#122

Post by drdeca » Mon, Jan 13, 2020, 4:52 PM UTC

brummm wrote: post #91

dnautics wrote: post #79

Earlier quoted context omitted.

I believe in gravitational waves, but specifically with LIGO I wish they did a better experiment with the multimodal observations. An easy one would be:. For an [n] month period blind all of the results, and mix them with 3X fake data. Then instruct traditional EM astronomers to search for EM phenomena corresponding to these signals. If only 25% of them correlate, we know the multimodal search is not working.

There is no believing in them. Gravitational waves have been observed and you can't "believe" or "not believe" in them anymore than you can "believe" or "not believe" in electricity.

A person can certainly disbelieve electricity, they would just be foolish to do so.

While I think a person would also be foolish to disbelieve gravitational waves, I think it wouldn’t be quite as foolish, because while we clearly measure gravitational waves, we don’t exactly use them to do (as opposed to “look at”) stuff, so a person’s everyday life is less impacted by disbelieving GW than by disbelieving electricity.

Re: Why the foundations of physics have not progressed for 40 years

#123

Post by achillesheels » Mon, Jan 13, 2020, 4:54 PM UTC

hhas01 wrote: post #34

7532yahoogmail wrote: post #2

I've read several of Sabine's blogs over several months. I think she has very good ends in mind, has courage to push back on corporate/academic inertia ... such inertia comes with any human organization ... On the negative side she's big on complaining but small on alternatives. She's also a bit too blunt/dismissive of people -- this from a person who also dislikes corporate happy talk. As such it's not clear if she'…

Aye, it’s easy to make criticisms (and Zeus knows the price of good science is eternal vigilance), but the easiest and most satisfyingly Ockhamite explanation of the slowdown in physics remains: all its low-hanging fruit is long since taken. And while there’s no harm in pondering the philosophical origins of the scientific method while debating where to go next, we should take care not to go backwards either, as that…

It’s amusing you jocularly employ Zeus in this conversation. Galileo, Descartes, Newton, Maxwell, etc. did not have Zeus on their minds, maybe it would be wise for you not to either?

Re: Why the foundations of physics have not progressed for 40 years

#124

Post by ssivark » Mon, Jan 13, 2020, 4:55 PM UTC

jjmorrison wrote: post #77

SiempreViernes wrote: post #71

Personally I find it amusing Hossenfelder is now invoking the need for learning philosophy of science, given how hostile she's been to it before. See for instance http://backreaction.blogspot.com/2016/08/the-unbearable-ligh... that begins with: "Philosophy isn’t useful for practicing physicists. On that, I am with Steven Weinberg and Lawrence Krauss who have expressed similar opinions." Though to be fair, she clarifi…

I thought the article was not great. But the fact that she's changed her mind on the topic makes me like her a lot more. How can we learn more if we don't change our mind?

Nothing wrong with changing one’s mind. But need to be thorough enough to provide a rigorous rebuttal of the arguments made by one’s past self :-)

Re: Why the foundations of physics have not progressed for 40 years

#125

Post by plmu » Mon, Jan 13, 2020, 4:55 PM UTC

rpz wrote: post #61

rpz wrote: post #35

In the spirit of pointing out inconsistencies...I am not a physicist, but something I've been confused about lately is why the action constant has a unit of seconds baked into it. Feels like E = hf is an experiment with a hard coded 1 second measure time. Why not express the relationship in terms of power? P=uf where u is the action constant without the seconds unit hard coded. And E=utf has a variable time parameter

Down votes? Care to explain? I'm just trying to learn here :)

Agree, I'm wondering too.

Re: Why the foundations of physics have not progressed for 40 years

#126

Post by jxy » Mon, Jan 13, 2020, 4:59 PM UTC

ISL wrote: post #86

I strongly disagree that the foundations of physics have not progressed for 40 years. We have been looking really hard for answers to persistent questions. While we have not found affirmative answers, physicists have systematically ruled out option after option after option. We have not yet discovered a unified-theory-of-everything, but we know a whole lot more about what that theory is not . Furthermore, the past 40…

「三十輻，共一轂，當其無，有車之用。埏埴以為器，當其無，有器之用。鑿戶牖以為室，當其無，有室之用。故有之以為利，無之以為用。」

Re: Why the foundations of physics have not progressed for 40 years

#127

Post by cambalache » Mon, Jan 13, 2020, 4:59 PM UTC

celticmusic wrote: post #32

ocfnash wrote: post #8

I dare say the author is right on many points but statements like: "But for all I can tell at this moment in history I am the only physicist who has at least come up with an idea for what to do." make it hard for me to share her point of view, especially as these ideas are not mentioned.

I'm not sure how you missed it, but she did give a recommendation. Attempt to resolve inconsistencies as a means of discovery.

This is so general and vague that it is useless, even more considering that the author has been saying the same for the last 10 years (the same timeframe her career progression stopped) and there is not a single valuable paper proposing a somewhat-valuable idea. I hate to sound like Lubos Motl (for the cognoscenti) but Sabine's criticism is trite.

Re: Why the foundations of physics have not progressed for 40 years

#128

Post by Anon84 » Mon, Jan 13, 2020, 5:00 PM UTC

leereeves wrote: post #117

Anon84 wrote: post #108

Earlier quoted context omitted.

When was the last time an experiment had a result that wasn’t explained by theory (supralumimal neutrinos aside)?

Observations of the cosmic microwave background, galactic rotation, gravitational lensing, and redshift led to the concepts of "dark matter" and "dark energy" that aren't yet explained by theory.

The cosmic microwave background was first detected in the 1960s, gravitaional lensing was predicted by Einstein in the early 1900s and redshift can be traced back to the later half of the 1800s (as an extension of the Doppler effect)...

Re: Why the foundations of physics have not progressed for 40 years

#129

Post by achillesheels » Mon, Jan 13, 2020, 5:00 PM UTC

hhas01 wrote: post #59

typon wrote: post #12

Earlier quoted context omitted.

Stop working on string theory, multiverse, or some of the other mainstream theories she mentioned. Start fresh about how to approach theoretical physics instead of taking the above mentioned theories almost as a given and trying to do science within that framework.

Except, string theory and multiverse aren’t theories . Heck, they’re not even hypotheses (since they offer no means to test them). They’re simple speculation; what philosophers right back to the ancient Greeks were only too happy to rest on for 2000 years, until Persian protoscientists, during their own all-too-brief golden age, annoyingly said “but wait, don’t you think we should at least test our beliefs before we…

Hence it is terrifying that a prestigious institute such as Cal Tech offers courses not on knowledge but on speculation (see bottom of list):

http://pma.caltech.edu/research-and-academics/physics/physic...

Re: Why the foundations of physics have not progressed for 40 years

#130

Post by orbifold » Mon, Jan 13, 2020, 5:02 PM UTC

celticmusic wrote: post #32

ocfnash wrote: post #8

I dare say the author is right on many points but statements like: "But for all I can tell at this moment in history I am the only physicist who has at least come up with an idea for what to do." make it hard for me to share her point of view, especially as these ideas are not mentioned.

I'm not sure how you missed it, but she did give a recommendation. Attempt to resolve inconsistencies as a means of discovery.

This is not a very original recommendation. In fact a major selling point of String Theory is that one can manage to derive both Einstein's Field equations and quantum field theory scattering amplitudes from its equations. This approach is currently the only one that can claim that for itself. Of course people like Hossenfelder never made an effort to understand String Theory in detail, so they can only make first order observations about the current state of the field.

It is also not true that no progress has been made in the understanding of String Theory in the last 40 years and it still seems like the best bet that could eventually generate a fundamental theory. What is missing is still a lot though:

- We don't seem to possess the correct mathematics to develop a non-perturbative formulation of String Theory and there are too many potential string backgrounds that we could expand around.

- It is also hard to derive the matter content of low energy effective actions from most brane configurations.

String theory provided major insight into non-perturbative quantum field theory as well. There is tons of examples, let me highlight one of them: The discovery of the Amplituhedron (Arkani-Hamed et al., 2012) was preceded by the discovery of the BCFW recursion relation (Britto et al., 2005), which in turn was motivated a relationship between perturbative Yang-Mills theory and the instanton expansion of a certain string theory in twistor space (Witten, 2003).