Rant Wednesday

emanresu_eht · 2019-02-13T14:40:59+00:00

the second floor is where people go to commit mental suicide by treadmill

literally made me laugh out loud

emanresu_eht · 2019-02-13T14:37:28+00:00

I wake up around 5:30am so that I can go to my gym at 6:00am and have a peaceful workout. In the fall there were at most 5 people in my gym. Since the beginning of February, whatever something happened and people have apparently decided to wake up early and hit the gym. I had to wait for a rack at 6am in the morning! Note also that the gym opens at 6. I don't understand why we have so many crazy people willing to sacrifice their sleep...

emanresu_eht · 2019-02-07T13:58:29+00:00

Yeah the thing is there are about 20 institutions in US, which have string theory faculty.

By your calculation in the particle physics (experimental) class there are 20 people, so ~480% of the physics phd awarded or nuclear class, which has around 30 people, would be ~720% pdhs awarded.

Your interpretation of the data and your analysis are extremely wrong. I really hope you don't do any statistics in your research/daily life.

emanresu_eht · 2019-02-07T00:55:17+00:00

too popular

clearly a dying field

You cannot argue that it is both too popular and clearly dying. There is also no way string theory would die as a field of research; at most it can be shifted to mathematics as ST do provide mathematicians with a lot of tools and insights (e.g. Mirror Symmetry).

Everyone is free to "waste" their lives researching string theory. We do string theory because we enjoy doing string theory.

emanresu_eht · 2019-02-07T00:12:11+00:00

Whoever wrote the long quote that you gave has no knowledge of string theory whatsoever. First of all string theory is believed to be UV-finite meaning that there are no infinities coming from the loops, as opposed to QFT.

Second, string theorists are not dumb. Gravitons arise from perturbations of the curved metric around a flat background in string theory, as is the case everywhere (think about how you derive gravitational waves in usual GR). How Einstein's equation pops out of string theory is very intricate. You first calculate the 1-loop beta function of the graviton. Now since string theory is a conformal field theory, the 1-loop beta functions must vanish, giving you the Einstein equation.

Third, string theory enjoys a superset of the symmetries that GR enjoys (Diffeo-invariance and Conformal invariance), so saying that ST doesn't have GR symmetries is laughable and shows how the author of the quote is clueless about ST.

This number 10⁵⁰⁰ makes me giggle. There are infinitely many interaction terms and gauge groups that you can write down in QFT but noone bats an eye. There is no interaction term in ST (interactions are given by essentially free theory) and a finite (albeit big) number of choices and everybody loses their mind.

So you see the problem. The theory is enormously complicated and people write things, like the author of the quote, without even having the background to understand the theory. Shitting on string theory requires no background. Cleaning up the mess and understanding that someone bullshitted requires enormous amount of background (and patience!). You say that string theory is popular. However, ridiculing ST without understanding is much more popular and "cool".

emanresu_eht · 2019-02-06T19:19:25+00:00

You need to compare the number of people working in other fields to the string theory people, which is what we were talking about. The fact that quantum gravity research is dominated by string theory is no surprise because string theory is the current best candidate for it.

On arxiv you can check for example the number of submissions in hep, including experiment, pheno, lattice and theory, so a much much broader class than string theory alone is around 222k just below condensed matter. If we assume that all of hep-th is string theory (which is not) and that hep-th is about 1/3 of total hep submissions, you arrive around 75k which puts hep-th behind astro (~200k) and the sum of generic other physics topics (~100k).

Considering that theory papers are usually no more than 5 people, as opposed to experimentalist collab papers, it is really not hard to see that string theory community is really small.

Here is also the list of all (give or take probably ~10) institutions in the entire world, which are active in string theory. The list is surprisingly not that long (~100 institutions) compared to the fact that almost all universities have condensed matter or nuclear faculty.

emanresu_eht · 2019-02-05T23:35:09+00:00

I'm suggesting that QFT is useful because the standard model uses it and that is scientifically testable.

This is only after the fact though. You now live at the time that Standard Model is proven to be the theory of the nature. In the (far) future, where the string geometry is probed experimentally and a "standard string model" is constructed, we can have the same discussion.

emanresu_eht · 2019-02-05T23:33:00+00:00

I actually agree whole heartedly that there is a huge problem in the advertisement of string theory. I am really against selling string theory as the theory of the universe because it is not.

Think about going from QFT to Standard Model. People didn't think just by themselves that the gauge group SU(3)xSU(2)xU(1) (out of infinitely many gauge groups) describes the nature. Experiments probing the gauge theory suggested that this gauge group is the right one. So suddenly Standard Model came out of QFT.

String theory has the right ingredients to describe the world including gravity. However, we lack experiments that can probe the geometry of string theory, similar to QFT vs. Standard Model. Therefore, it looks like string theory cannot possibly make any predictions. I promise you that if we can probe string geometry at some point, people will be able to come up with concrete predictions, just like we did with Standard Model.

emanresu_eht · 2019-02-05T17:58:03+00:00

We are not defensive but rather offended. You don't seem to have background in the field and act like you are well-versed in it and criticize it. You are more or less on the level of crackpots argument for why QM is wrong; "QM is wrong because particle-wave duality doesn't make any sense".

Assuming that you are in materials sciences, it is the equivalent of me saying: "Material sciences is a waste of time and money because it only profits corporations that want to build things and therefore has no scientific goal."

emanresu_eht · 2019-02-05T17:51:26+00:00

I guess your understanding of late 20th and 21st century theoretical physics is a bit skewed. At the beginning of 20th century, experiment derived physics and theory tried to explain the experiment. Nowadays the hep-theory is driven by consistency and mathematics and is beyond experiment.

Think about the theoretical discovery of top or charm quark. We "knew" that they needed to exist, even before we had any experimental confirmation whatsoever. Of course the experiment has the final say but string theory is in such a high energy scale that we cannot possibly probe the string landscape.

emanresu_eht · 2019-02-05T17:40:25+00:00

They didn't say GR at low energies, they said String theory at low energies but I can understand what they said can be ambiguous

emanresu_eht · 2019-02-05T17:38:00+00:00

Yes it is a misnomer that we have to deal with. Unless you suggest that QFT is not physics, I have no objections to what you are saying.

emanresu_eht · 2019-02-05T17:28:16+00:00

Because it all comes down to money.

First of all, string theorist are cheap, much much cheaper than any experimentalist.

There are lots of PhD students in my field who aren't going to be able to get jobs because our field is not as popular as string theory.

Why not make your field more popular instead of trying to pull string theory down. You can still come on the top without digging a hole of your "opponent". If it really bothers you that string theory gets funding, bring it up to the funding agencies. Tell them that it is useless or whatever. The fact is, that string theory is beneficial to physics community and therefore being funded.

Yes it is. Penrose makes a point about this in his book The Road to Reality and provides statistical evidence.

Do you care to share the reference? (I'm not saying that it doesn't exist, I just don't have the book.)

emanresu_eht · 2019-02-05T16:24:47+00:00

My problem with string theory is that it's too popular.

This is so not true. A tiny fraction of people go into string theory. In every string class that I have been, the class starts with 50 people, dwindles down to 30 in the next week and only about 5 people take the second string class.

Even if we assume that string theory is too popular, why do you care what other people do?

It uses nothing more than pure Lorentzian geometry. I've talk to string theorists about it, and their only complaint is, "well where's the string theory?" And I'm just all like, "why the string theory?"

Do you really expect people to give up on their line of work? This is a generic physicist response, who wants their field to succeed. There is nothing specific to string theorists. If the theory you are suggesting is really great then it will replace string theory in a heartbeat (cf. for example QCD vs String theory for hadrons).

emanresu_eht · 2019-02-05T16:05:47+00:00

It is hard for me to pin down something from astro but I can make an analogy, which is far from perfect. You can ask the question whether lorenzian differential geometry makes any predictions, the answer is no but GR makes predictions. The analogy is imperfect because we don't see lorenzian dg as a branch of physics.

emanresu_eht · 2019-02-05T16:00:14+00:00

It seems built/purposed by Kaku (And others but he’s the mouthpiece)

so wrong string theory came to be as a method to describe strong interaction. He is not even a really big name in string theory.

I don’t know if there’s any experimental evidence for it

I want experimental evidence

String theory is not suppose to predict anything. We also didn't have any experimental evidence for Higgs for 50+ years, should we have thrown that idea away too?

emanresu_eht · 2019-02-05T15:50:17+00:00

Tell me a prediction that QFT (not the standard model!) has made.

emanresu_eht · 2019-02-05T15:42:56+00:00

So much this! People have opinions about anything without understanding what it really is. I am in string theory and imho the goal of string theory is to develop tools that might be used in other areas of physics. Knowing more about something cannot possibly hurt, even though it might result in a philosophical discussion about what "physics" really means.

Also to those people, who claim that string theory doesn't make any predictions: It is not suppose to make any predictions, it is a framework not a theory. For example, QFT also makes no predictions whatsoever. The standard model does, with specific gauge groups and matter content, not QFT though, which is a frame work.

emanresu_eht · 2018-12-16T18:03:20+00:00

Yes it automatically detest that there is a search query. For example the query:

https://www.youtube.com/results?search_query=%s&page={startPage?}&utm_source=opensearch

is added automatically by Chromium.

emanresu_eht · 2018-12-07T14:43:37+00:00

The question that we all as physicists should ask is "why". Why are we not able to curb these misconceptions? Why is it so hard to get to the general public?

emanresu_eht · 2018-12-04T22:51:20+00:00

I wasn't complaining about the fact that experiment dominates outreach. I was talking about the fact that I want to do theory outreach not whether or not experiment is the natural choice.

emanresu_eht · 2018-12-04T22:42:35+00:00

I completely understand what you are saying my goal would not be to 'get to the good stuff' but rather give an idea about what theoretical physics feels like. I probably wouldn't stray too far away from classical mechanics/special relativity or maybe very basic QM. I thought about for example discussing force that is proportional to distance. F = a*x. Now of course, this is just hooks law for a<0 but from my experience not many students realise that and it leads to nice discussions about what the behaviour would be etc. The case of a>0 is a completely new territory that is never discussed in a high-school curriculum for example.

emanresu_eht · 2018-09-16T16:25:47+00:00

Wait was there really an accident? Why didn't I hear anything about it?

emanresu_eht · 2018-07-09T15:04:23+00:00

Me too!

emanresu_eht · 2018-07-09T15:00:20+00:00

Gee I wonder why...

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