Nabeshin said:
Really? There's no reason NOT to say this. The Higgs is no different than a standard scalar field within the context of classical GR. So of course it's going to be a source for gravitation. You don't really even need to get into a theory of quantum gravity for that. Of course, nobody has verified this and probably never will verify it, but theoretically this is the default case by a very large margin.
Of course there is a reason not to say it. There is no evidence that GR applies at the quantum level. Being a source of gravition is not neccessarily same as saying curved space at a quantum level. We also cannot say what does contribute to gravity. We know form observations, that total mass contributes, but we cannot say if for example, virtual particles contribute at all. In fact, we can almost certainly say it would not make sense to talk about GR at the quantum level. Just like it does not make sense to apply Lorentz transformations (special relativity) at the quantum level. For special relativity you need to apply the Dirac equation at the quantum level. Until we find and prove the validness of the logical equivalent of the Dirac equation for general relativity, and extrapulation down to the quantum level anything is at best speculation... For all I know something completely different happens at the quantum level to space, that just extrapulates on a large scale to the bending of space.
As an example, let's look at a very simple model (one so simple I know it doesn't work). Let's say space is tiled like one of the hexegon grids used in board games. Let's say particles are like playing peices that consists of a group of tiles, each of which is the exact same shape as the tiles of the board. Now we make a simple rule, that we cannot place two tiles ontop of each other. So if I add an electron to the board, I have to pick-up and remove the tiles where the electron is at. However, we also make the second rule that we cannot perminently remove tiles from the board. So I then have push other tiles out of place to put back down the original tiles. All the while, I have to maintain the grid pattern, so I constantly keep pushing the tiles back into a grid pattern wherever I can. Eventually, over a large enough area I manage to get everything back close enough to the original grid pattern, it looks the same as when I started. But someone carefully examining the board would notice there is a slight rise, in the board into verticle caused be the peices pushing on each others edges. So I now have a curvature to my space on a large level, even though my particle itself did not curve space. All of it's tiles are perfectly flat, and in the same shape as the rest of the tiles. In fact anywhere I go on the board, locally I cannot see a curvature. It is only when I consider the combined effects of all the tiles, is there a curvature of space.
While as I said, the above model is overly simplistic, and will not actually work, it gives you an idea of how a unified theory could well have no curvature space by fundamental particles, such as the Higgs, but still give rise to a curvature at the macro level.
Ultimately, it is doubtful one could ever measure if space is curved by a particle such as a Higgs, but one could eventually develope a model that gives a reasonable description of what happens to space at that level, and gives solid predictions as to what happens at and observable level as a consequence beyond what you expect from GR.
It is interesting to take a step back and ask how we even know what we do know. For example, how do we know it is mass that causes the curvature of space and not say for example baron number? Surely for any object large enough to measure the baron number will be directly proportional to it's rest mass. We can say that an electron is effected by gravity, but then so is light. But does that mean it contributes to the curvature of space? Would such a model give a dramitically different description of how an electron acted within a gravitational field? Really, I've never research this so, I would have a hard time really arguing against a baron number hypothesis. I would only point to the periodic table and point out the mass of elements does not exactly scale with baron number. So it would at least in theory be possible to test such a hypothesis. I do not know however, if anyone has ever done so. I seem to remember vaguely reading about a model that actually predicted a baron number scaling of curvature of space. So this is not wild conjecture, it just presenting a possibility someone else has examined.
Bill