My dad and I think that the universe is free falling, what do you think?

Question

Experts say that the universe is being expanded and accelerated by "dark energy", but we think that everything in the universe is at a constant free fall. Whenever someone is in space, they are really free falling around the earth, but its gravity holds them close. So why isn't this the case with galaxy's, etc. Any opinions?

Answer 1

Firstly, only some experts hypthosise about dark energy, it is far from an accepted scientific fact.

But what you are talking about is completely unrelated. Yes, the galaxys are all free falling and everything in the universe is, because everything in the universe is under the effects of gravity from the rest of the universe, since gravity is action at any given distance.

But, to say the Universe is free falling implys there is a 'container' the Universe is in, just as the Universe is the container for all the matter within it. Not only that, but it also implys that in the 'container' the Universe exists within, there is gravity that acts as the gravity within our Universe does.

These are both enormous assumptions and could be as easily as they could be wrong. There is simply no way of observing that which is outside of existance as we know it, so we can't know that, at least for now.

Even so, the expansion of the Universe is unrelated.

Also, don't pay too much attention to the person who says 'Universe' means 'Everything that is'. Atom means 'Indivisible', but that's clearly not true. It's just a name. There may be other Universes and there may not be, again, this is not something we can observe.

So, unless that responder has observed and recorded data from outside of the Universe, he is only stating his opinion.

Answer 2

If an object is in free fall, then by definition the only force acting on it is gravity. If the only force acting on the clusters of galaxies that are moving away from each other was gravity, then the expansion of the Universe would be slowing down. But the expansion is actually speeding up! This was a pretty revolutionary discovery, to say the least! And it means that there is some other force acting on these clusters of galaxies, making them accelerate despite the pull of gravity - they call it dark energy, since they really have no clue what it is. So since there are at least two forces acting, the clusters of galaxies aren't in free fall.

Answer 3

Free fall does not mean there is no gravity. It just means that you are falling at the same rate as an object, such as the earth, is turning below you. If you stop moving around you would fall to the earth from its gravity. Its just that the net effect of the attraction of gravity and the centrifugal force that is moving them away balance each other so it is zero.

Galaxy clusters are actually not moving because of a force on them (although individual galaxies within a cluster may be moving toward each other from the gravitational attraction). They are moving apart because space is expanding due to the big bang and they are riding in this space that is growing. The usual analogy is to imagine them stuck on a balloon that is expanding as you blow it up. The galaxy clusters move apart because the space between them is expanding.

Dark energy is a force astronomers have discovered that is making this expansion of space go faster and faster. It may be seen as a type of anti-gravity.

Answer 4

Falling requires gravity. There is no gravity in space, therefore no falling. It is considered to be expanding b/c the bodies that make up the universe are getting farther away from each other.

There is no 'dark energy' causing the universe to expand. Because bodies in motion tend to stay in motion until acted upon by an outside force, the universe has continued to expand since the Big Bang.

There is no up or down in space.

Answer 5

Galaxies, etc. are in "free fall" -- which just means that gravity is the force that keeps them going around each other. Electric force on galaxy orbits is practically nil.

The word "universe" means "everything there is". The universe is not being accelerated -- its the things in the universe that are being accelerated away from each other. There is no "other" for the universe to accelerate away from.

Answer 6

Gravity holds galaxies together. The gravity from the milky way does affect other galaxies. According to the equasion the force of gravity never reaches absolute zero no matter how far away you get from the source.

Answer 7

If you can find the answer to that question, then you have solved the biggest question in cosmology right now! It's truly a mystery as to why the universe seems to be accelerating outwards when one would expect that gravity would slow the rate of expansion.