What happens if the density of the universe is less than the critical density?

If the density of the universe is less than the “critical density”, which is proportional to the square of the Hubble constant, then the universe will expand forever. If dark energy in fact plays a significant role in the evolution of the universe, then in all likelihood the universe will continue to expand forever.

Is the density of the universe equal to critical density?

WMAP and Dark Matter / Dark energy WMAP determined that the universe is flat, from which it follows that the mean energy density in the universe is equal to the critical density (within a 0.5% margin of error). The actual density of atoms is equivalent to roughly 1 proton per 4 cubic meters.

Is the universe above critical density?

If the ratio is greater than one, then the actual density of the Universe is greater than the critical density, and thus the Universe will eventually become closed and will ultimately end up collapsing in on it self.

When the density of the universe is greater to the critical density it is referred to as which of the following?

If the density of our universe is greater than the critical density, our universe is ‘closed,’ which means our universe will eventually stop expanding and start contracting back on itself. If the density of the universe is equal to the critical density, then we live in a ‘flat’ universe.

Why is the critical density of the universe important?

The ‘critical density’ is the average density of matter required for the Universe to just halt its expansion, but only after an infinite time. If the density of matter in the Universe is high (a closed Universe), self-gravity slows the expansion until it halts, and ultimately re-collapses.

Is the density of the universe decreasing?

The density of matter decreases as the universe expands because the volume of space increases. Although little is known about dark energy, its density is expected to change slowly or not at all as the universe expands.

Why is the density of the Universe so close to the critical density?

If the density of matter in the Universe is low (an open Universe), self-gravity is insufficient to stop the expansion, and the Universe continues to expand forever (albeit at an ever decreasing rate). This is referred to as a flat geometry, and the density is called the ‘critical density’.

Is the density of the Universe decreasing?

Is the universe becoming less dense?

If the universe is infinite, it has always been infinite. At the Big Bang, it was infinitely dense. Since then it has just been getting less dense as space has expanded.

Is the density of the universe increasing?

The density of matter decreases as the universe expands because the volume of space increases. (Only a small fraction of matter is in the form of luminous stars; the bulk is believed to be dark matter, which does not interact in a noticeable way with ordinary matter or light but has attractive gravity.)

Why is the density of the universe so close to the critical density?

What is meant by the critical density of the universe?

The ‘critical density’ is the average density of matter required for the Universe to just halt its expansion, but only after an infinite time. A Universe with the critical density is said to be flat. In a closed Universe, locally parallel light rays converge at some extremely distant point.