Cosmology/space-time question

Factual Questions
1

Hi everybody. I have a question about the nature of space-time and the universe. As I understand it, the medium of the universe is space-time, within which everything exists.

If, in simplistic terms, this is accurate, are there any hypotheses that suggest:

• that within space-time there are fundamental units, roughly analogous to pixels in a 2D monitor;

• that these “space-time pixels” are fixed in place in space-time, moved only by gravitational waves (with the movement of the space-time medium itself);

• that everything we can see and detect (even at the sub-atomic levels) are simply patterns created by configurations of these pixels; and

• these configurations of pixels comprise sub-atomic and atomic etc structure at the location of each affected pixel.

As an analogy, even on the highest definition monitor, regardless of how realistic it is, everything that is seen is a function of the pixels. So, an object that we see moving on a TV screen, for example, only has the appearance of motion.

Similarly, has anyone hypothesized that if, for example, I am walking down the street, that the velomont at 2:06:33 pm is only a manifestation of a specific set of space-time pixels at a specific moment of time, while ten yards forward, at 2:06:42 pm, a completely different velomont, while looking identical to the previous velomont(s), is being manifested by a different set of space-time pixels?

I hope this makes some sense (IAMA physicist so this could be absolute BS) and I apologize for the length of this post but I am curious.

Thank you very much

2

It is known that quantum mechanics and general relativity must be reconcilable in some way or another. It is not currently known how that might be done. It is possible (but not known) that the reconciliation might involve quantization of spacetime. If spacetime is quantized, then it is possible (but not certain) that the quantization might be of a form that might be described as “pixels”. And if the quantization is of a form that might be described as “pixels”, then it’s possible (but maybe not) that the pixels might in some sense be “stationary”.

Are you familiar with cellular automata, like Conway’s game of Life? There are some (including Stephen Wolfram, creator of Mathematica and Wolfram Alpha) who think that the Universe might function as a cellular automaton, at some sub-microscopic level, and there really isn’t any way yet to rule out the possibility. That sounds like it might be fairly similar to what you’re describing.

3

Chronos has nicely discussed a few of the hypotheses that are out there. But I feel obliged to point out that there is currently no evidence that spacetime is anything other than continuous. All of the successful models of fundamental physics to date treat spacetime as though there were an infinite continuum of points between any two points in space, just like you can find an infinity of real numbers between any two real numbers. (“Successful” here meaning “with experimental evidence to back them up”.)

Your “pixel” idea implies that there would be some smallest scale in space, below which you can’t meaningfully subdivide space any further. It’s possible that this is the case; after all, our experiments can’t measure arbitrarily small distances, so all we can say is that if this “smallest length scale” exists, then it must be smaller than such-and-such length. It’s also possible that even weirder things happen at small scales that we haven’t thought of yet. We simply don’t know.

4

Chronos & MikeS,

Thank you very much for the replies - lots to consider.