What are dark matter and dark energy, and how are they affecting the universe?

Answer 1

Dark energy and dark matter describe proposed solutions to as yet unresolved gravitational phenomena. So far as we know, the two are distinct.

Dark matter originates from our efforts to explain the observed mismatch between the gravitational mass and the luminous mass of galaxies and clusters of galaxies. The gravitational mass of an object is determined by measuring the velocity and radius of the orbits of its satellites, just as we can measure the mass of the sun using the velocity and radial distance of its planets. The luminous mass is determined by adding up all the light and converting that number to a mass based on our understanding of how stars shine. This mass-to-light comparison indicates that the energy in luminous matter contributes less than 1 percent of the average energy density of the universe.
There is certainly more matter in our galaxy and other galaxies that we cannot see, but other evidence indicates that there is an upper limit to the total amount of normal matter present in the universe. By normal matter, I mean stuff made out of atoms. Recently, NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) satellite made precision measurements of the imprint of sound waves on the cosmic microwave background, produced some 400,000 years after the big bang. Because sound propagation depends on the properties of the medium--as anyone who has played with a helium balloon knows--the pattern of the sound waves viewed by WMAP is an indicator of the abundance of hydrogen and helium in the universe. (All other elements were built from these basic building blocks.) These and other results agree with the theoretical predictions of the primordial abundances of the light elements as a result of the nuclear processes that took place in the first three minutes of the universe--also known as big bang nucleosynthesis. Ultimately, very strong arguments have been made that at most 5 percent of the mass-energy density of the universe, and 20 percent of the mass of clusters, is in the form of atoms.

What could dark matter be? Many physicists and astronomers think dark matter is probably a new particle that so far has eluded detection during particle accelerator experiments or discovery among cosmic rays. In order for a new particle to behave as dark matter, it must be heavy (probably heavier than a neutron) and weakly interacting with normal matter so that it does not easily lead to light-producing reactions. The prototypical dark matter candidate particle is something like a neutrino, though all known types of neutrinos are too light and too rare to explain dark matter.


How does dark matter affect the universe? The dark matter problem can also be viewed as a question of the nature of clustering matter. Dark matter must be the basic building block of the largest structures in the universe: galaxies and clusters. Without dark matter, the universe would be a very different place, according to current theories

Answer 2

DARK MATTER - The observed motions of large-scale structures like galaxies can't be explained by the gravitational force of known mass, therefore science concludes that there must be some other mysterious kind of mass that so far hasn't been directly detected but that influences the observed galactic movements.

DARK ENERGY - Recent observations show that the expansion rate of the universe is increasing instead of decreasing as seems more reasonable. Science has thus deduced that some mysterious, unknown type of force is counteracting the force of gravity that should be slowing down the expansion rate.

Answer 3

Dark matter is a substance that was created by scientist. It was created by them because they needed it to exist so they could easily explain how galaxies hold together. Basically, it allows there math to work properly.

Dark energy is like "The Jedi Force". Its an imaginary force to explain why the space between galaxies is increasing.

Answer 4

Dark matter is something invented to make otherwise flawed calculations add up.
Take 5+5=10. But you need it to add up to 12. Solution? Invent dark matter.

Answer 5

There is no answer to this - scientists only have theories so far. There are experiments in various stages of development to find the answers. Anyone who claims an answer to this question is not well informed.

Answer 6

It's only a theory and has no basis if fact or reality.