A phenomenon is probably “an observable fact or event.” The term came into its modern usage through the German philosopher Immanuel Kant, who contrasted it with the noumenon which cannot be directly observed. However, the term originates from the late 16th century via late Latin from Greek phainomenon “thing appearing to view”, based on phainein “to show” and might describe a remarkable person, thing or event while it as well includes the object of a person’s perception; what the senses or the mind notice.
It’s at least a real idea. In 1908, Hermann Minkowski discovered that if you treat the rate and duration of spatial displacement (time) as just another dimension (metric, not realm) in math equations along with the three classical spatial dimensions, you can accurately predict that displacement (motion) without having to directly observe the object in motion. Thus was born the concept of spacetime.
Matt O’Dowd is an Australian astrophysicist and associate professor in the Physics and Astronomy Department of the City University of New York. He is a writer and host of PBS Space Time on YouTube and breaks down both the basic and incredibly complex sides of space and time.
Explore the outer reaches of The Universe, space, the craziness of astrophysics, the possibilities of sci-fi, and anything else you can think of beyond planet Earth.
A black hole is a place in space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying. Because no light can get out, people can’t see black holes. They are invisible. Space telescopes with special tools can help find black holes. The special tools can see how stars that are very close to black holes act differently than other stars.
Scientists think the smallest black holes formed when The Universe began. Stellar black holes are made when the center of a very big star falls in upon itself, or collapses. When this happens, it causes a supernova. A supernova is an exploding star that blasts part of the star into space. It is widely believed that supermassive black holes were made at the same time as the galaxy they are in.
Quasars shine so brightly that they eclipse the ancient galaxies that contain them. They are distant objects powered by black holes a billion times as massive as our sun.
Astronomers called them “quasi-stellar radio sources,” or “quasars,” because the signals came from one place, like a star.
Specifically, a quasar is a supermassive black hole that is actively feeding on matter (and antimatter for that matter). The infalling matter has swirled into a disk that has heated up and it shines so brightly that its light drowns out the rest of the galaxy around the black hole.
Much more observation and study, particularly the results of the Hubble space telescope, has now identified around 200,000 quasars. The evidence indicates that they largely came into existence around 12 billion years ago when galaxies were being quickly formed in close proximity and they commingled the black holes that form at galactic centers.
Supermassive black holes pull in so much matter that the disc of material being pulled in lights up. Even though the size of this disc is thought to be no larger than the Solar System, the light emitted can be as much as 1,000 times as bright as the entire Milky Way which contains perhaps 400 billion stars. Quasars are indeed impressive.
Wormholes are consistent with the general theory of relativity, but whether wormholes actually exist remains to be seen.
A wormhole could connect extremely long distances such as a billion light years or more, short distances such as a few meters, different universes, or different points in time.
However, if you don’t have something threading through them to hold them open – the walls will basically collapse so fast that nothing can go through them. Holding wormholes open would require the insertion of something that anti-gravitates – namely, negative energy.