Eli5 if the universe is expanding, then why isn’t the earth, and everything in it (us) getting measurably bigger too?
In: 4
Imagine you are standing in one spot wearing roller skates. On your left is a 250 lb NFL lineman. On your right is a 50 lb child. They each begin pulling on you in opposite directions. Which way will you go?
The universal expansion is like the 50 lb child, gravity is like the 250 lb lineman. At distances smaller than galactic clusters, gravity wins.
Space is expanding, not matter.
The space between galaxies, and the space between molecules are both expanding equally.
There is a lot more space between galaxies, so it expands a lot more (because there is more space to expand). The space between atoms and molecules is so small, that the rate of expansion is so slow that the molecules pull themselves back together.
At the current rate of expansion, everything in our local galaxy cluster is still being held together gravitationally, but even if it were much faster it would take a lot to start ripping apart the Earth, much less our own galaxy.
Space is expanding, not matter.
The space between galaxies, and the space between molecules are both expanding equally.
There is a lot more space between galaxies, so it expands a lot more (because there is more space to expand). The space between atoms and molecules is so small, that the rate of expansion is so slow that the molecules pull themselves back together.
At the current rate of expansion, everything in our local galaxy cluster is still being held together gravitationally, but even if it were much faster it would take a lot to start ripping apart the Earth, much less our own galaxy.
Space is expanding, not matter.
The space between galaxies, and the space between molecules are both expanding equally.
There is a lot more space between galaxies, so it expands a lot more (because there is more space to expand). The space between atoms and molecules is so small, that the rate of expansion is so slow that the molecules pull themselves back together.
At the current rate of expansion, everything in our local galaxy cluster is still being held together gravitationally, but even if it were much faster it would take a lot to start ripping apart the Earth, much less our own galaxy.
The universe is expanding because the big bang was, well, big, but everything in it has been cruising along just under gravity since then (yes, I’m going to ignore dark energy). So, we have this big explosion in space and stuff comes flying out. Now, a bit of that stuff collapses under gravity and sticks together. Things far away from our new [star, galaxy, cluster] are still moving away from it, but our star doesn’t care. It just keeps happily doing star things while the rest of the universe keeps moving away.
The universe is expanding because the big bang was, well, big, but everything in it has been cruising along just under gravity since then (yes, I’m going to ignore dark energy). So, we have this big explosion in space and stuff comes flying out. Now, a bit of that stuff collapses under gravity and sticks together. Things far away from our new [star, galaxy, cluster] are still moving away from it, but our star doesn’t care. It just keeps happily doing star things while the rest of the universe keeps moving away.
The universe is expanding because the big bang was, well, big, but everything in it has been cruising along just under gravity since then (yes, I’m going to ignore dark energy). So, we have this big explosion in space and stuff comes flying out. Now, a bit of that stuff collapses under gravity and sticks together. Things far away from our new [star, galaxy, cluster] are still moving away from it, but our star doesn’t care. It just keeps happily doing star things while the rest of the universe keeps moving away.
As a thought experiment, can we prove that it’s not? Our measuring devices would also grow at the same rate, our perceptions would change at scale …
As a thought experiment, can we prove that it’s not? Our measuring devices would also grow at the same rate, our perceptions would change at scale …
As a thought experiment, can we prove that it’s not? Our measuring devices would also grow at the same rate, our perceptions would change at scale …
Latest Answers