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TomLikesPhysics
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I hear all the time that the universe is expanding. Those that mean that my meterstick becomes a little bit longer each day (or second)?
 2 years ago
 2 years ago
TomLikesPhysics Group Title
I hear all the time that the universe is expanding. Those that mean that my meterstick becomes a little bit longer each day (or second)?
 2 years ago
 2 years ago

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TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
So what is expanding? Just space but my meterstick stays the same? So there is some kind of selection of what gets longer what does not?
 2 years ago

ramkrishna Group TitleBest ResponseYou've already chosen the best response.0
actually the distance between any two heavenly bodies are increasing at any time. but not the particles on the planet.
 2 years ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
So the vacuum is expanding?
 2 years ago

ramkrishna Group TitleBest ResponseYou've already chosen the best response.0
objects in the vacuum are expanding............
 2 years ago

ujjwal Group TitleBest ResponseYou've already chosen the best response.0
In general, the universe is expanding refers to the fact that the galaxies are moving away from each other continuously..
 2 years ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
So I could but my meterstick in vacuum and therefore it would expand!?!?!?
 2 years ago

Carl_Pham Group TitleBest ResponseYou've already chosen the best response.2
There are two ways to think about this. First, in the easy way, where you consider matter separate from the space it occupies, you can say that, yes, your meter stick expands  or rather, starts to, but every time the space between the atoms and molecules increases by a hair, the strong forces between the atoms and molecules immediately pull them back to the correct equilibium distance, and nothing changes overall. You might say the meter stick is continually sliding back into equilibrium as the underlying space expands. The other way, more true to Einstein, looks upon matter as just a manifestation of the local curvature of space. From this point of view, the expansion of the universe is just the universe becoming, on average, less dense. But as it turns out, matter resists becoming less dense  because it attracts itself. So the way the universe on average can become less dense is if the reduction in density is confined to those regions that are already nearly empty. Regions in which matter is already dense stay dense. The inhomgeneity of the universe steadily increases. Indeed, from this point of view the universe ends up as an infinitely dilute gas of black holes, with every bit of the universe either perfectly empty (between the black holes) or infinitely dense (within the black holes).
 2 years ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
Ah now I get the idea. The reason for this expansion is dark energy/unknown?
 2 years ago
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