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Approaching 50 Years of String Theory

math.columbia.edu

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Re: Approaching 50 Years of String Theory

#111

Post by nsoonhui »

mishaevtikhiev wrote: post #102

I have a PhD in high energy theoretical physics (hep-th for short) and I've written a paper on string theory, so I'd like to comment on some things: 1. I think there are two reasons why string theory is cool (other people may have different opinions). Please note that none of these two reasons are directly related to the extension of Standard Model. 1.1. String theory is the only theory so far that can mix gravity an…

Thanks for the comment that exposes the nuances. As a non physicist who is interested in physics, I would say that the predicament is that we simply don't have enough data to tell how to improve our physics theory, but we have too many physicist working in the field, so ideas just get staled.

Is that a correct assessment?

Re: Approaching 50 Years of String Theory

#112

Post by tpoacher »

gnfargbl wrote: post #50

People often say that the problem with string theory is that it doesn't make any prediction, but that's not quite right: the problem is that it can make almost any prediction you want it to make. It is really less of a "theory" in its own right and more of a mathematical framework for constructing theories. One day some unusual observation will come along from somewhere, and that will be the loose end that allows som…

> the problem is that it can make almost any prediction you want it to make

In logic this is either the principle of "contradiction elimination" or a "vacuous truth". Depending on how you look at it. i.e. given sufficiently bad premises, you can prove anything.

Re: Approaching 50 Years of String Theory

#113

Post by utopiah »

ecosystem wrote: post #93
PunchyHamster wrote: post #48

Earlier quoted context omitted.

Might as well fund someone researching whether quantum theory run on little gnomes, if there is no serious path to verification after 50 years, why not quantum gnomes?

On this topic (parallel postulate), it took ~2000 years from Euclid and then 3 people all came to the same conclusion independently within ~10-20 years. Progress is weird.

Is it so weird? See Multiple discovery https://en.wikipedia.org/wiki/Multiple_discovery and Zeitgeist https://en.wikipedia.org/wiki/Zeitgeist namely that there might, or might not, be objective knowledge out there describing properly an objective World but we as a specie do chip at it with itself over time. When a new discovery in any field is made it propagates through our social network and tools we have for it, e.g. cafes, scientific journal, Web. As soon as something is discovered most of us connected enough get the new tool or perspective, update our Worldview and chip it at it again. IMHO this way it seems pretty normal that things hitherto unknown, no matter for how long, become knowable to seemingly independent discovers.

Re: Approaching 50 Years of String Theory

#114

Post by machinationu »

GMoromisato wrote: post #105

What experiment(s) would we have to run to see deviations from the Standard Model and be able to come up with newer models (maybe String Theory maybe not)? Is it just about higher energy particle collisions? Or does it involve things like doing experiments next to a black hole?

we already have experimental data for deviations from the standard model: neutrino mass for example

or dark matter

Re: Approaching 50 Years of String Theory

#115

Post by CubicLettuce »

tim333 wrote: post #73

String theory has always seemed intuitively wrong to me. From Wikipedia: >In theories of particle physics based on string theory, the characteristic length scale of strings is assumed to be on the order of the Planck length, or 10E−35 meters Yet electrons repel each other over distances of many meters by I think the virtual exchange of photons. How on earth would that work? How does your photo string know to head to…

[dead]

Re: Approaching 50 Years of String Theory

#116

Post by atakan_gurkan »

XorNot wrote: post #88
atakan_gurkan wrote: post #19

Earlier quoted context omitted.

To make this valuable, it should produce a limited set including standard model. If you produce pretty much everything one can dream of, that does not carry predictive power. What does string theory predict that (1) is within experimental reach in, say, 5 years (2) if not found, would prove it wrong. Was there ever anything satisfying these two simultaneously? AFAIK,the answer is "no".

You write this as though reality is a 4X game and we're obviously wasting time not clicking on the other item in the tech tree to optimize the build.

No, I am simply stating what is expected of a good scientific theory in physics. Such a theory should have power to explain things as well as make new, testable predictions. It is valuable to collect our present information under one umbrella, but if everything falls under that umbrella, it may as well not exist. String theory does not have predictive power (mostly because of energy scales mentioned elsewhere in this discussion, unless someone comes up with an ingenious way to probe its domain with low energy experiments), and its explanatory power is not very useful since it explains both reality and things out of reality, indiscriminately.

Everyone is free to pursue what they want. I did not comment on that at all. You click on whatever part of the tech tree you want. However, my expectation is that the string theory does not have the qualities of a scientific theory that improves one's knowledge about universe.

Re: Approaching 50 Years of String Theory

#117

Post by XorNot »

gnfargbl wrote: post #94
XorNot wrote: post #87

Earlier quoted context omitted.

There is not a "huge chunk" of the theoretical physics community working on string theory, and their never was. For one, it is far less common a topic of research now then it was earlier when it was more popular, but even then "huge" was really "a lot of universities had a grant for string theory investigation because it looked promising". It mostly hasn't worked out and now people are moving on to other things. The…

Huge is a subjective term, but go and count the number of participants at Strings 2025 [1]. Then realise that is just one of many conferences [2]. It's still a very big field. [1] https://nyuad.shorthandstories.com/strings-conference-abu-dh... [2] https://www.stringwiki.org/wiki/Conferences

A meaningless statement if you aren't going to introduce any points of comparison. But I would hardly call 735 conference participants a huge conference. Like, that's big but there are lot more then 735 theoretical physicists.

Re: Approaching 50 Years of String Theory

#118

Post by setopt »

ecosystem wrote: post #23
setopt wrote: post #6

Earlier quoted context omitted.

Physicist here. Would you like to enrich our world view by linking to counter-examples? My understanding was that string theory being more "hypothetical physics" than "theoretical physics" at this point is still a pretty legit criticism.

The legit criticism with a legit recommended change is even better. A time and technological gap always exists between theory and a plan for experimental confirmation. Some gaps are fairly short. String theory's gap is undoubtedly long, not for lack of resources. This gap justifies tapering the allocation of attention and research resources (funding, students, etc), which got lopsided following the strong marketing c…

I tend to agree. Science funding is unfortunately a limited resource, and I would like to see different approaches explored in more detail, which unfortunately would imply less (but not zero) funding to string theory. Not zero, because we also don’t want the competence built up in string theory groups to die out completely, in case that remains our best lead.

To borrow a compsci analogy, we tried the depth-first search going in the string theory direction, maybe it’s time to switch to breadth-first for a while, to see if there are any viable and useful theories with less distance from the ones we have today. Maybe it doesn’t have to be a "theory of everything" either, we can initially settle for a "theory of more".

Re: Approaching 50 Years of String Theory

#119

Post by Tadpole9181 »

dgfl wrote: post #82
Tadpole9181 wrote: post #69

Earlier quoted context omitted.

> We should stop funding research into prime numbers. They're stupid and useless. Who cares about them, if they will never be used for anything? Number theory should be stopped, you may as well research gnomes. I imagine this is what you would have sounded like 100 years ago.

You may be understating how much 15 orders of magnitude are. The only truly exponential technological progress we’ve ever had, transistors, only scaled by ~5 orders of magnitude in feature size. Thermal engines went from maybe 0.1% to ~50%, less than 3 orders of magnitude, in about 200 years. There’s very fundamental physical laws that suggest that engines are done, and transistor scaling as we have known it for 30 y…

Are you seriously insinuating that string physics are asking for this collider you alone entirely made up? As if people who actually do study string theory are too stupid to know primary school math and this criticism is somehow high-brow and novel?

Not to mention you entirely missed the point of what I said. There is research into the most niche, useless fields imaginable, because not every endeavor taken by every human being needs to be profitable or applicable. Sometimes people are just really good at making jigsaws or want to make a stinky chemical or get fascinated with properties of prime numbers.

And then, sometimes, those turn out to be the fundamental underpinnings of an entire generation of economic and military strategy. You can't often know what spurs what in that sense.

Re: Approaching 50 Years of String Theory

#120

Post by gnfargbl »

XorNot wrote: post #117
gnfargbl wrote: post #94

Earlier quoted context omitted.

Huge is a subjective term, but go and count the number of participants at Strings 2025 [1]. Then realise that is just one of many conferences [2]. It's still a very big field. [1] https://nyuad.shorthandstories.com/strings-conference-abu-dh... [2] https://www.stringwiki.org/wiki/Conferences

A meaningless statement if you aren't going to introduce any points of comparison. But I would hardly call 735 conference participants a huge conference. Like, that's big but there are lot more then 735 theoretical physicists.

Claude tells me that there are about ~5000 theoretical high energy physicists actively publishing as tracked by INSPIRE-HEP (the de facto search engine in that field). If we estimate that about a third or half of string theorists take part in Strings in a given year -- because there are other big conferences like String Pheno that will be more relevant for many -- then we have something like 30-50% of high energy theorists working on string theory.

I agree that people should be "moving on to other things," but I'm not seeing the evidence that they actually are.

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