So long as we stick with gravity and how qm clashes melodiously with general relativity I guess we will be ok?
You said you understood the idea of a heavy object sitting in spacetime and thereby warping things toward it. I expect you have heard the analogy where you have something like a pencil or a wineglass (a rolly object) lying on a mattress (a warpable surface) and it lies still just fine, but then when you stick a more massive object in the middle of the mattress, like a typewriter or a television, all that stuff suddenly rolls right towards because it changes the shape of the mattress and thereby warps stuff toward it.
This is an excellent analogy from the general relativity viewpoint in that it causes people to nod their head about how it works even though they can't think in Einstein-level math all day. But really it doesn't explain anything, and neither does the math, it just says that gravity affects the math in a specific definable way. And that's fine for gravity, for the moment.
Meanwhile though light for example, one of our other relativity goodies in the math, has some properties that we have a lot more trouble getting people to swallow with simplistic analogies and universal math. For example light behaves like a wave, like sound for example, but has no medium to be traveling through. In other words, something is traveling, like what the atomic chemists would call a particle would, but it doesn't have any mass and moves in all directions at once, unlike a particle. The word "wavicle" was invented at this point, and some of the guys actually doing the math were able to nod their heads at that, but really it isn't a very good explanation either even for scientists.
Menwhile the guys who actually make the bombs and run the accelerators and generally investigate new ways of blowing up the earth, they were seeing something odd. Based on the math that they did, relating to very small things rather than large areas like relativity, some of the fundamental components they were breaking up particles into had equally odd impossible properties.
We ended up with a bestiary of different pseudo-particles in two families, the fermions and the bosons. The bosons, like the photon that turns out to explain light, take up space but have no mass. The fermions have mass, but don't take up any space! This, you will notice, makes it fairly hard for the mass to be the thing that is directly warping the space, it not having any of its own to work with.
Some of the bosons though, the pseudo-particles that relate to space and are expressed as fields, they do warp space, and they are attached to the fermions in normal matter. Sadly, the ones we have actually seen so far in the course of smashing things do not include the graviton, the one that would theoretically mediate the field that holds the universe together in the big vague way that general relativity requires. We have seen the ones that mediate the fields that hold atoms together though, so we certainly aren't giving up, the general idea is to find one like that only much Much weaker.
Cavediver is pointing out that some of the new attempts at unified theories are suggesting that perhaps we don't need another particle at all, perhaps the entities that hold neutrons together could also make gravity work if you just added a whole gob of extra dimensions instead, with one version of the force being diluted by going in every direction through uncounted branes and another being strengthened by having its force trapped in a very small circular dimension curved in on itself. But really, it's all gibberish until someone manages to catch signs of it in one of the big particle accelerators. (And only slightly more sensible for years afterward, I expect.)
Anyway to summarize, fields are the expression of the quantum "particles" that have no mass and mediate space, the bosons. Electromagnetism, the stuff that makes light work, is a field. Gravity, the stuff that warps smaller masses towards larger ones, is a field. Fields tend to express themselves at the maximum speed possible in our spacetime, C = 186000 miles or 300000 kilometers per second, and in all directions at once. The other set of particles, the fermions, which do have mass, are normally bound up in these fields in various ways, which is lucky because the relationship between the two seems to make our spacetime what it is.
*Oh, and the reason these little guys are allowed to break all the rules is because they are technically smaller, shorter or less whatever than one of the measurably smallest possible things that are normally possible in our curved spacetime. For example, nothing that has mass and takes up space can possibly be smaller than Planck's Constant (the distance light travels in the smallest measure of time). Yet when we smash things that are almost that small already in two, we still get stuff. But, it's stuff that does one or the other, not both.
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