I'm standing stationary to Earth and the light that hits me reads "t = -8". Additionally, I use angular size to determine the Earth is 8 ly away. I now accelerate to 0.99c. Despite the LC and the relativity of simultaneity, the actual light I see is still the same, right? Earth at t=-8, 8 light years away?
@Slereah Well...you can dispose of all the "string" language and just say you have some 2D CFT with a 10D target space and then write down the sum over worldsheets that is the string scattering amplitude
The "worldsheets" are "objects with limited extent" as they are compact, but...well, I don't think you can really say that the theory "relies on object of limited extent".
Likewise, you wouldn't really say that ordinary QFT relies on point particles, would you?
You have two perspectives: Worldsheet and spacetime.
In the worldsheet perspective, you have a 2D worldsheet with a CFT living on it, and it happens to have a 10D spacetime as target space. The string partition function is then defined by certain sums over such theories. Nowhere in this perturbative approach is any field living on the spacetime, it's just the target space
In the spacetime perspective, you take the tree-level results of the string scattering and look for what "normal" QFT living on spacetime would produce these. That's when you find various 10d SUGRA theories, these are called the low-energy effective actions of string theory.
The interpretation as coordinates in spacetime is "external" in the sense that the formalism doesn't really tell you what the space $X^\mu$ takes values in should be
Since you only defined the S-matrix perturbatively by "brute force", you cannot to my knowledge, in the full string theory, compute something like "expectation values"
@Danu Well, I think almost everyone believes that either a) the analogy to Feynman diagrams is so obvious that it's not a big deal b) there is a non-perturbative formulation of string theory (M-theory, F-theory) waiting to be found.
If you conceive of the fields $X^\mu$ as the actual coordinates of the string in the spacetime, then the classical e.o.m. describe the motion of a string floating around.
The interpretation as coordinates in spacetime is "external" in the sense that the formalism doesn't really tell you what the space $X^\mu$ takes values in should be
Questions which have been (or are in the process of being closed as a duplicate) often get answers posted anyway. What's the best way to deal with these answers? The problem with upvotes (even to the answers, let alone to the question) is that it more or less pulls focus away from the preferred...
let $a,n \in \mathbb{Z}$ where $1\leq a \leq n$ and $1 < n$. I am told to prove that if $(a,n) \ne 1$ (they share a common factor) there exists an integer $b$ such that $ab \equiv 0~(mod~n)$ i.e. $\frac{ab}{n}$ leaves no remainder. basically, $ab=nq+r$ where $r=0$ so $ab=nq$. Shouldn't there always be a combination so that they are equal? even if $(a,n)=1$ I feel like there should still be a combination where $b=n$ and $q=a$
@ArnoldNeumaier ok. anyway theres an openminded/ enthusiastic/ similar-thinking audience/ "fan club" of at least 2 to digest and possibly even further develop/ expand on your (new) ideas esp wrt "interpretations" here on SE chat if you have some time, even intermittently.
Questions which have been (or are in the process of being closed as a duplicate) often get answers posted anyway. What's the best way to deal with these answers? The problem with upvotes (even to the answers, let alone to the question) is that it more or less pulls focus away from the preferred...
I upvoted a post mistakenly. Then I tried to cancel my vote but I couldn't because my reputation isn't enough. How can I cancel my vote?
