Good visualization but inaccurate. Space between galaxies in a cluster and even the stars in a galaxy is also growing. The difference is in scale. There’s so much distance between galactic clusters and the largest structures of the universe that added up that expansion amount is so much bigger. The balloon analogy with galaxies as dots on the surface is closer since the dots also do grow some, but the balloon would have to be huge to capture a good scale comparison.
Are you sure that galaxies are growing? They’re gravitationally bound enough to have organized orbits, do those orbits get larger over time?
do those orbits get larger over time?
Yes, I think they do.
I think that expansion doesn’t increase distance, but velocity between objects (or so was my interpretation back when I looked at the formulas). That means that moving objects speed up over time. As such, orbital velocities increase, too, and that lifts their orbit - similar to when a rocket on a closed orbit propulses forward.
But I might be wrong; I feel 70% certain about this one.
But I might be wrong; I feel 70% certain about this one.
You should downgrade your certainty. By a lot.
The expansion is an expansion of space, and therefore explicitly increases the distance between galaxies. It does not, and cannot increase the speed at whoicj those galaxies travel through that space.
Right now, there are galaxies moving away from us at rates higher than the speed of light, a thing which is physically not possible if the expansion is due to an acceleration of the galaxies themselves.
You’ve misunderstood things completely backwards.
My understanding was that in a gravitationally bound system like that, the orbits would be slightly larger (or slower for the same distance) based on the rate of expansion and the distance, but not grow any unless the rate of expansion increases. Like maybe the earth is a few angstroms farther from the sun than in a not expanding universe, but that number doesn’t change as long as the expansion keeps going the same. Same for galaxies and clusters.
At the planetary scale, such a change would be completely overpowered by other orbit defining effects, like resonance, mass flow/loss, and even drag.
At the cluster scale, I can absolutely see spacetime expansion overpowering gravity.
At the galaxy level, I can’t tell. Does spacetime expansion limit the size of galaxies? Is that limit shrinking due to the acceleration of expansion? Are galaxies under that limit larger than otherwise expected? Is this effect large enough to effect the speed of galaxy rotation and does it need to be taken into accout when measuring the effects of dark matter?
There’s no center of the surface of the balloon (approximating the balloon as a sphere and ignoring the nipple).
If you are standing on the earth, there is no center of the surface of the earth. The actual center of the earth requires movement in the 3rd dimension, but the surface is 2 dimensional.
If our universe is hyper spherical, the “center” would be something unreachable; it would require moving in the 4th spacial dimension.
Yeah I get that, but there is no evidence of a 4th spacial dimension, so it’s really just creative writing at this point.
so thats why Galactus has such a hard on for the universe
Also, don’t forget to flour your galaxies in order to keep them in their respective places and prevent them from all rising to the top of your universe.
Can we just not use metaphor for everything? It’s like building a new car only out of old parts people are familiar with. 😹
I read “3cm” as “Jam” somehow and was very confused. For a bit, I thought the raisins were holes to inject the jam into to make a jam-filled cookie.
Read this at first as “if you bake it, he will come” and I was like “I dunno if I’d go that far. Depends on what kind of jam, to be honest”
