Is the rate at which the universe expanding increasing?

[T.O.E Dream]

I was thinking of an idea in my head about a week ago, but it would need the rate of the expansion of the universe to increase over time (this is different from it just expanding at a constant rate). Today, i was reading about dark matter and it had stated that it might be the reason why the rate of expansion is increasing. Can someone clear things up? Is the rate increasing or is the universe expanding at a constant rate and is there already a confirmed explanation to this?

Thanks in advanced!

 

[nicksauce]

The rate of expansion is indeed increasing. This has nothing to do with dark matter, but rather what's known as "dark energy" or "cosmological constant". Most people believe that dark energy has something to do with the energy of empty space, but no one is quite sure yet. Also note that the expansion was not always accelerating, this only started very recently (in cosmological terms). In the past, regular matter was the dominant form of "stuff" in the universe, and because gravity attracts, it pulled things together, slowly the expansion down. Only recently did dark energy surpass matter as the dominant "stuff" in the universe, and dark energy has the property that it is repulsive, so it speeds up the expansion.

 

[T.O.E Dream]

Well can the acceleration of the expansion of the universe be a property of spacetime itself. Maybe all constants change as the universe expands so time probably speeds up making the universe expand faster.

 

[nicksauce]

There is no evidence to suggest anything like this.