Hassaan Saleem

In the last few years, I, many of my friends and colleagues have noticed the fact that a lot of people (physicists and non-physicists) have started to criticize string theory. So much so that it is becoming the “new cool thing to do”.

This post explores the possible reasons why this is happening. This is not a post to give arguments against these criticisms, although I may mention some of the criticisms for reference. Many writings to answer the criticisms already exist. If I decide to write about it, that will become a separate post. Before we start, I want to mention that I am a theoretical physicist, working on string theory, who frequently listens to and tries to engage with the criticisms of strings.

The criticism of string theory is not a new thing. However, it seems that a lot of people who are “criticizing” string theory now are doing so because they have either listened to or read the writings of well-known critics of string theory on the internet. It is pretty hard to find a “critic” of strings who has actually studied the theory in detail. You can tell the shallowness of their understanding of the subject by the quality of criticisms that they are offering. Very frequently, they regurgitate the criticisms from well-known critics and quote them verbatim.

I have to mention that some critics have studied the theory and frankly, their criticisms are much more interesting and meaningful to engage with than an overwhelming majority of the critics. This reminds me of a sentence from J. Conlon’s book, ‘Why String Theory’. He writes, “Scepticism about string theory tends to diminish as technical knowledge about the subject increases”.

So, why is this happening? Is it happening because the predictions of string theory are extremely hard to test? Well, many people would say that this is the reason. However, this is just a consequence of the smallness of the Planck scale and this is the reason because of why other theories of quantum gravity like LQG are also hard to test. But again, this is not a post to refute the arguments against strings.

I think the main reason for this increased criticism is that in the last few years, many critics of string theory have become very vocal on the internet (I don’t want their voices to be curbed as they have the right to speak). One might argue that people like Lee Smolin and Peter Woit have been doing it since the 2000s, so what’s new about that?

I think the addition of more people in this game is one thing. People like Carlo Rovelli (who I respect a lot but disagree with on some things), Sabine Hossenfelder (whose popular science work I greatly admire but strongly disagree with on a lot of things), Brian Keating (I don’t like a lot of things that he does) and Eric Weinstein (I don’t like him, period) have changed the game.

I won’t deny that these people have likable personalities and a lot of non-expert audiences can agree with them even if they say something which is not true because they like them. So much so, that their audience will attack anyone on the internet who disagrees with them. There have been incidents like that and I can talk about them if somebody asks.

Now you can ask, “But Hassaan, isn’t this the same way how string theory got its popularity as well?”. I will argue that there are significant differences. String theory gained popularity in the 90s and early 2000s. At that time, there was hardly any social media and we all know how people have gone much more into echo chambers after social media (echo chambers did exist before but now the situation is much worse).

The three people who had the most part in popularizing string theory were Brian Greene, (through his TV series and writings), Michio Kau (through his videos in the early days of social media), and Joseph Polchinski (mainly through his writings). On top of that, people were impressed by the personality and knowledge of Ed Witten.

Now, Michio Kaku made some claims about string theory that I can’t defend. Moreover, the claim that string theory will give you a theory of everything was very plausible at that time. But now, we know that the theory is much harder and it will take a long time. So, we shouldn’t say now that we will have a theory of everything in 4 to 5 years.

I think that apart from these claims, any other claim that these people made at that time can be defended. Why is that the case? Because these people were experts on the subject and knew what they were talking about. The speculation part (that strings will become the theory of everything in some years) was not right because no one is an expert at speculating.

Now you may ask, “But Hassaan, what about the non-expert audience that was dogmatic about string theory and tried to defend string theory without knowing enough?”. Well, I do see such people even today and I would say just one word for them, CRINGE. They are very awkward.

I don’t like many things that non-expert people used to say in support of strings. I think that the people who were popularizing strings should have educated their popular audience about this. Probably they did try to educate them, but a better job could be done.

Now, let’s come to the present moment. A similar trend is visible for the non-expert audience of the critics of strings now. On top of that, it is more dangerous because the present state of social media can make you much more dogmatic. You get a lot of “politics” vibes from a lot of discourse that goes on Physics Twitter, Physics YouTube, and Physics FB for example.

Another reason why this uninformed criticism of strings is increasing in popular audiences is that there are hardly any channels of communication that debunk a lot of wrong claims that are made about string theory on the internet.

We can contrast it with the past when people like Brian Greene, Cumrun Vafa, Michio Kaku, and Joseph Polchinski used to do it. Greene is not that active in debunking these claims now but talks about them when they appear on public platforms. Vafa is active in swampland research and talks about these claims now and then. Kaku has lost most of his credibility by making ridiculous claims and Polchinski is no longer with us (remember that he was the one who tackled Smolin’s claims in “Trouble with Physics” by writing his article “All strung out?” in American Scientist).

The efforts of these people and the new generation who is studying string theory are not even comparable to the efforts that string theory critics are putting into spreading their message (even if many claims that they make are wrong).

Take the recent example of Eric Weinstein going to Joe Rogan’s podcast (which is the biggest podcast, whether one likes it or not) and spewing out all kinds of nonsense about string theory and Ed Witten in particular. I haven’t seen any serious effort to tackle that nonsense except for Kaku appearing on a podcast and talking about it (but that isn’t close to being adequate).

On Physics Twitter, some string theorists and some people who are sympathetic to string theory do try to debunk such claims but that is not even comparable to the anti-string rhetoric that goes on there.

I think string theorists should take more time than they already are and engage with the criticism of string theory and if any claims are nonsense, debunk them. Of course, we don’t have to engage with and debunk everyone’s claims but if there is some person with considerable influence who is making wrong claims, then they should be debunked. Moreover, if there is some good argument against string theory, we should engage with that argument instead of turning our backs on it.

I understand that engaging with these claims takes out of our precious time that could be used for research. I have this train of thought too. I could be doing my research instead of writing this article. However, here is two points that I want to raise.

Firstly, not every string theorist has to do it. A significant number of string theory people doing it on a regular basis and getting people to listen to them will do the job. Secondly, the public believing in wrong and defamatory claims about your field is never good for your field. A communication channel to debunk such claims and to engage with criticisms is seriously required.