Spacetime – 4 dimensions united

“I Really Appreciate Science. Technology and Cute Experiments are Cool, too!” – In a fourth installment I would just summarize the last three installments by saying that as we probe deeper into stuff, it gets simpler to explain and hopefully to understand. But there are still questions. For example, since spacetime is so important to our universe and stuff, we should ponder why do we have the spacetime we do? Why four dimensions, 3 of space and 1 of time?

This question has been pondered immensely by physicists, and calculations made of various possibilities in a “universe of stuff” like ours. I’m posting a diagram by a very cool physicist named Max Tegmark (ThanX Julie !) that was previously posted on Facebook summarizing those ponderings. Note the small white square, That’s us! It turns out that if our existence were of smaller spatial dimensions, it would be too simple and nothing would really occur or evolve in spacetime. Certainly not a self-conscious species like us. If it had larger spatial dimensions, it would be too unwieldy and unstable. We wouldn’t survive too many evolutions before the universe would be completely done in. Now all this does not mean things didn’t evolve this way at first as energy dissipated into chaos, but it was too simple, or too unstable, or limited to time particles (tachyons) etc., that it went no where fast and had to re-form. Or, in competition with our universe it could not survive. Finally, our set-up was the only one “working” and here we are in 3D space and 1D time, holding on with our fingernails.

So, not only is a universe like ours the only kind that can survive its own creation, but also its the only kind of universe that has the capability of becoming self-aware. The freedom of motion permitted by the three dimensions of our space is just enough, but not too much, to enable them to adjust their paths subtly and to avoid disaster. What it also means is that it can never be absolutely symmetric. Somethings have to be off-kilter, just enough, for evolution to do it stuff.

julie chart

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