The Expansion of the Universe
The following seems to be missed by many anons:<p>* spacetime itself literally “creates itself out of nothingness”. We say it “stretches”, but don&#x27;t picture a string of cheese “thinning out” but rather something of constant density being continuously expanded.<p>* local groups (of galaxies) are gravitationally bound i.e they won’t scatter around and they attract each other with gravity so they will stay together even though more spacetime is created inside of them.<p>* in the empty “space” between local groups something (dark matter? Dark energy? ) causes this steady continuous creation of new spacetime<p>* this creation of spacetime is itself accelerating, but this is not speed, so distant local groups are not “moving away from us” but are being “displaced away from us”. Hence the displacement rate is allowed to be faster than the speed of light (since it’s not a speed)<p>* every single object in the universe moves at exactly and precisely the speed of light c through spacetime. Objects at rest (a completely stationary astronaut stranded in the empty  space between local groups) is also moving at the speed of light in spacetime: he is moving only through time.<p>* A photon is moving only through space and has no time<p>Sources: The Elegant Universe, Brian Greene, ScienceClic YouTube, and my memory of these