What kind of matter in the universe that has gravity but does not emit light?

dark matter
Unlike normal matter, dark matter does not interact with the electromagnetic force. This means it does not absorb, reflect or emit light, making it extremely hard to spot. In fact, researchers have been able to infer the existence of dark matter only from the gravitational effect it seems to have on visible matter.

Does time not exist in space?

Time is a complex subject for physicists. Although there is nothing in physics that says time must flow in a certain direction, scientists generally agree that time is a very real property of the Universe.

When did the universe become transparent to light?

At about 370,000 years, neutral hydrogen atoms finish forming (“recombination”), and as a result the universe also became transparent for the first time.

Will the universe continue to expand without limit?

For sufficiently large values for the dark energy content of the universe, the expansion rate of the universe will continue to increase without limit. Gravitationally bound systems, such as clusters of galaxies, galaxies, and ultimately the Solar System will be torn apart.

How does dark energy affect the expansion of the universe?

The thinning of matter over time reduces the ability of gravity to decelerate the expansion of the universe; in contrast, dark energy (believed to be a constant scalar field throughout our universe) is a constant factor tending to accelerate the expansion of the universe.

What happened to the mass of the universe after the Big Bang?

Between 10 seconds and 377,000 years after the Big Bang. After most leptons and anti-leptons are annihilated at the end of the lepton epoch, most of the mass-energy in the universe is left in the form of photons. (Much of the rest of its mass-energy is in the form of neutrinos and other relativistic particles).