Does the universe stretch or expand?

The straight answer is that the universe doesn’t expand into anything. There is no space “out there” for it to expand into. What the cosmic expansion does is stretch space itself, as if space were made of some kind of stretchy rubber material. Real space is three-dimensional, as we can also move vertically up and down.

Is the space between planets expanding?

The spaces between planets and stars isn’t growing. Only the distances between galaxies which aren’t gravitationally bound to each other is increasing. Because space itself is expanding.

How is new space created?

The Universe began as a hot dense plasma in explosion. But the Big Bang was not an explosion in a pre-existing space. Space just means the distances between the particles, so space came into existence as average distances between the first particles increased.

Where does the universe expand?

The universe is everything, so it isn’t expanding into anything. It’s just expanding. All of the galaxies in the universe are moving away from each other, and every region of space is being stretched, but there’s no center they’re expanding from and no outer edge to expand into anything else.

Why does the universe keep expanding?

Astronomers theorize that the faster expansion rate is due to a mysterious, dark force that is pulling galaxies apart. One explanation for dark energy is that it is a property of space. As a result, this form of energy would cause the universe to expand faster and faster.

Where does the universe expand into?

Does the universe stretch or compress?

If you consider a Universe filled with radiation, because the wavelength lengthens as the Universe expands, the “space stretches” analogy works very well. If the Universe were to contract instead, “space compresses” would explain how the wavelength shortens (and energy increases) equally well.

What happens to the energy when the universe expands?

As the Universe expands, its volume is increasing while the energy density doesn’t change, and therefore the total energy increases. It’s as though new space is getting created due to the Universe’s expansion.

Why is the universe curved?

If your Universe has nothing in it at all, no matter or energy of any form, you get the flat, unchanging, Newtonian space you’re intuitively used to: static, uncurved, and unchanging. If instead you put down a point mass in the Universe, you get space that’s curved: Schwarzschild space.

Is there an expansion of spacetime?

In spacetimes like these, however, there’s no expansion. There’s no change in the distance or the light-travel-time between any points within this spacetime. With just one (or fewer) sources inside, and no other forms of energy, these “model Universes” really are static.