Dark Matter: Invisible, Mysterious and Perhaps Nonexistent
Galaxies don't have enough regular matter to keep them from flying apart, scientists have been telling us for years. So there must be a bunch of unseen "dark matter" lurking in every galaxy.
But dark matter has never been directly detected, and nobody knows what it might be made of. A few scientists remeain skeptical. To a lay person, it might sound downright crazy.
Now a new study suggests there may be no such thing as dark matter.
Fred Cooperstock of Northeastern University and Steven Tieu at the University of Victoria say Einstein's theory of general relativity can explain the cohesiveness of individual galaxies including our Milky Way.
Here's the thinking:
Newton's laws of physics explain why our solar system stays together. But the planets are negligible in the overall gravitational scheme, with the Sun being the total ruler and containing 99.86 percent of all the mass.
The same Newtonian physics were long ago applied to galaxies, and the rotation of stars couldn't be explained, so dark matter was invented to make theory work.
But a galaxy is much different than the solar system, Cooperstock explains. The conglomeration of all the matter -- stars, black holes, gas, and dust -- is collectively the source of the galactic gravity. Even a black hole at a galaxy's center typically packs less than 1 percent of the galaxy's overall mass.
The overall galaxy's gravity "feeds its own motion ... unlike the case of the solar system," Cooperstock told SPACE.com.
Oct 10, 2005
Robert Roy Britt, Senior Science Writer, Space.com
Galaxies don't have enough regular matter to keep them from flying apart, scientists have been telling us for years. So there must be a bunch of unseen "dark matter" lurking in every galaxy.
But dark matter has never been directly detected, and nobody knows what it might be made of. A few scientists remeain skeptical. To a lay person, it might sound downright crazy.
Now a new study suggests there may be no such thing as dark matter.
Fred Cooperstock of Northeastern University and Steven Tieu at the University of Victoria say Einstein's theory of general relativity can explain the cohesiveness of individual galaxies including our Milky Way.
Here's the thinking:
Newton's laws of physics explain why our solar system stays together. But the planets are negligible in the overall gravitational scheme, with the Sun being the total ruler and containing 99.86 percent of all the mass.
The same Newtonian physics were long ago applied to galaxies, and the rotation of stars couldn't be explained, so dark matter was invented to make theory work.
But a galaxy is much different than the solar system, Cooperstock explains. The conglomeration of all the matter -- stars, black holes, gas, and dust -- is collectively the source of the galactic gravity. Even a black hole at a galaxy's center typically packs less than 1 percent of the galaxy's overall mass.
The overall galaxy's gravity "feeds its own motion ... unlike the case of the solar system," Cooperstock told SPACE.com.
Oct 10, 2005
Robert Roy Britt, Senior Science Writer, Space.com
