4 ms·

Did I read it wrong, or does the universe expand at 10% of speed of light!? Could that possible be why the measurements are off? A close object vs an object ver

by z3t4 2y ago

Did I read it wrong, or does the universe expand at 10% of speed of light!? Could that possible be why the measurements are off? A close object vs an object very far away might look like they are in different places relatively.

mr_mitm 2y ago
Rest assured, this has been taken into account. The scientists who spend their life working on this topic have had the same thoughts you had within minutes of learning about the problem. It's extremely basic stuff actually.
- z3t4 2y ago
  If it's extremely basic stuff and they've spent their entire life working on it, why did the two teams find different results? Thinking of objects moving 10% of light speed, or even two times the speed of light away from you, is not intuitive to a layman, and I can't imagine the Math.
  - mr_mitm 2y ago
    Because the problem lies somewhere else which is not extremely basic. Relativistic effects are not the issue here.
feoren 2y ago
The observable universe has a radius of about 14 Gigaparsecs. If H0 is 67.4 km/s/Mpc, then a naive calculation puts the edge of the observable universe expanding at 943,600 km/s, or about 3 times the speed of light. Of course we still observe this as merely "close to" the speed of light, but the point is that most of the universe is shooting away from us so fast that we will never see them as they are "now", even if we wait billions of years. We have no way of ever interacting with most of the "modern" universe, even theoretically. They might as well be in different universes. All we will ever see is their images from billions of years ago, even if we wait billions of years from now.
evanb 2y ago
It's likely you read it wrong; there is no sense in which the universe's expansion has a fixed speed. The Hubble parameter is speed/distance [the figure's axis is km/s/Mpc, for example]. That is the natural unit to explain an expansion rate: things that are farther away ALSO move away from you faster (because the space between you and them all grows at a fixed rate).

by z3t4 2y ago

mr_mitm 2y ago

Rest assured, this has been taken into account. The scientists who spend their life working on this topic have had the same thoughts you had within minutes of learning about the problem. It's extremely basic stuff actually.

z3t4 2y ago
If it's extremely basic stuff and they've spent their entire life working on it, why did the two teams find different results? Thinking of objects moving 10% of light speed, or even two times the speed of light away from you, is not intuitive to a layman, and I can't imagine the Math.
- mr_mitm 2y ago
  Because the problem lies somewhere else which is not extremely basic. Relativistic effects are not the issue here.

feoren 2y ago

The observable universe has a radius of about 14 Gigaparsecs. If H0 is 67.4 km/s/Mpc, then a naive calculation puts the edge of the observable universe expanding at 943,600 km/s, or about 3 times the speed of light. Of course we still observe this as merely "close to" the speed of light, but the point is that most of the universe is shooting away from us so fast that we will never see them as they are "now", even if we wait billions of years. We have no way of ever interacting with most of the "modern" universe, even theoretically. They might as well be in different universes. All we will ever see is their images from billions of years ago, even if we wait billions of years from now.

evanb 2y ago

It's likely you read it wrong; there is no sense in which the universe's expansion has a fixed speed. The Hubble parameter is speed/distance [the figure's axis is km/s/Mpc, for example]. That is the natural unit to explain an expansion rate: things that are farther away ALSO move away from you faster (because the space between you and them all grows at a fixed rate).