These measurements, together with other scientific data, have confirmed the existence of dark energy and provide an estimate of just how much of this mysterious substance exists. The rate of expansion and its acceleration can be measured by observations based on the Hubble law. This leads to a repulsive force, which tends to accelerate the expansion of the universe. The even distribution means that dark energy does not have any local gravitational effects, but rather a global effect on the universe as a whole. It is distributed evenly throughout the universe, not only in space but also in time вЂ“ in other words, its effect is not diluted as the universe expands. Dark energyДark energy makes up approximately 68% of the universe and appears to be associated with the vacuum in space. If one of these theories proved to be true, it could help scientists gain a better understanding of the composition of our universe and, in particular, how galaxies hold together. One theory suggests the existence of a вЂњHidden ValleyвЂќ, a parallel world made of dark matter having very little in common with matter we know. Dark matter candidates arise frequently in theories that suggest physics beyond the Standard Model, such as supersymmetry and extra dimensions. However, they would carry away energy and momentum, so physicists could infer their existence from the amount of energy and momentum вЂњmissingвЂќ after a collision. If they were created at the LHC, they would escape through the detectors unnoticed. Many theories say the dark matter particles would be light enough to be produced at the LHC. Experiments at the Large Hadron ColliderВ (LHC) may provide more direct clues about dark matter. Here's a sobering fact: The matter we know and that makes up all stars and galaxies only accounts for 5% of the content of the universe! But what is dark matter? One idea is that it could contain 'supersymmetric particles' вЂ“ hypothesized particles that are partners to those already known in the Standard Model. Dark matter seems to outweigh visible matter roughly six to one, making up about 27% of the universe. 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. This means it does not absorb, reflect or emit light, making it extremely hard to spot. Unlike normal matter, dark matter does not interact with the electromagnetic force. Hours of Operation: April 15 - May - 9:30 am - 5:00 pm June - August - 9:00 am - 5:00 pm September-October - 9:30 am - 5:00 pm (weather dependent) Last tour starts 30 minutes before closing. This strange and unknown matter was called вЂњdark matterвЂќ since it is not visible. We are one of the select Family Approved Attractions of the Black Hills which offer a quality experience you will enjoy. They think something we have yet to detect directly is giving these galaxies extra mass, generating the extra gravity they need to stay intact.

The same is true of galaxies in clusters, which leads scientists to believe that something we cannot see is at work. They are rotating with such speed that the gravity generated by their observable matter could not possibly hold them together they should have torn themselves apart long ago. Galaxies in our universe seem to be achieving an impossible feat.

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