system
Given the following post, respond as if you're commenting on Reddit:
human
String theory, what is its status as of now?

String theory has been around for some time now and gets a lot of attention in popular science. It would be nice if the physicists here could tell me whats the status of string theory as of now

*Has there been any experimental evidence so far or suggestion for the existence of strings?

*Have we been able to work back from first principles to derive accepted theories like QED or QCD ?

*Why do a lot of physicists think that strings could be the answer? Has there been any alternative theories that work better?

EDIT: Thanks for the answers! After reading it I am left with one question though

*Has string theory become too mathematical? Has it grown into branches of Math not too accessible to physicists?
gpt
>*Has there been any experimental evidence so far or suggestion for the existence of strings?

No, and given the tiny distance scale on which string theory operates, it is hard to imagine what experimental evidence might even be feasible to obtain.

>*Have we been able to work back from first principles to derive accepted theories like QED or QCD ?

It is not clear if string theory even has a unique solution; the best we can say is that string theory has the ingredients necessary to incorporate the Standard Model, but we do not have a direct path to show that string theory predicts the Standard Model.

>*Why do a lot of physicists think that strings could be the answer? 

The appeal of string theory was that for the first time, we had a theory that combined gravity and quantum mechanics in a way that appeared successful, restricted certain other features of the theory (dimension of spacetime, symmetry groups) that were arbitrary in particle theories, did not require *renormalization* (a logically sound procedure that many find distasteful), and provided a natural geometrical interpretation of interactions.

>Has there been any alternative theories that work better?

Among those who work on string theory and related topics, the current thinking is that string theory is actually one corner of a deeper underlying theory called M-theory, which involves a broader range of geometrical objects, and which incorporates the 5 distinct string theories plus 11-dimensional supergravity as special cases of M-theory.

There is an alternative approach to quantum gravity called *loop quantum gravity* that has also garnered attention.  Loop quantum gravity approaches things by directly modifying the structure of spacetime.