Table of Contents
What is the relationship between dark matter and gravity?
According to cosmologists’ prevailing theory, dark matter pervades pretty much every galaxy, providing the extra gravity that keeps stars from swirling out into space, given the speeds at which astronomers see the galaxies rotating.
What force can explain the rotational speed change as dark matter is moved in the galaxy?
We call this mysterious extra matter Dark Matter because it cannot be detected directly using light of any kind. Dark Matter can be detected astronomically only by its gravitational effects on stars and gas: It makes the outer parts of galaxies rotate faster than expected from their starlight.
What is modified gravity theory?
MOND is an example of a class of theories known as modified gravity, and is an alternative to the hypothesis that the dynamics of galaxies are determined by massive, invisible dark matter halos.
What is meant by dark matter why do astronomers conclude that the Milky Way contains dark matter?
Dark matter was initially called “missing matter” because astronomers could not find it by observing the universe in any part of the electromagnetic spectrum. This material appears to have mass (and therefore generates gravity), but it does not appear to absorb or emit any electromagnetic radiation.
Can relativity explain dark matter?
For most astronomers, it is just common sense that dark matter accounts for approximately 85\% of the matter in the universe. Recently, astronomer Alexandre Deur suggested that the theory of relativity itself may explain a phenomenon widely regarded as evidence for dark matter.
Is there a new theory of gravity in distant galaxies?
Observations of distant galaxies have seen signs of a modified theory of gravity that could dispense with the invisible, intangible and all-pervasive dark matter. The Hubble Space Telescope captured this image of NGC 5949 some 44 million light years away.
What is dark matter and why does it matter?
By some estimates, dark matter makes up about 85 percent of all the matter in the universe. It’s said to interact with light and visible matter only through gravity, and it explains the observed anomalies in distant galaxies.
Is there a faint gravitational effect on distant stars?
In research published in November in the Astrophysical Journal, the scientists report tiny discrepancies in the orbital speeds of distant stars that they think reveals a faint gravitational effect – and one that could put an end to the prevailing ideas of dark matter.
What is the Modified Newtonian dynamics theory (Mond)?
The authors say the effect cannot be explained by dark matter theories, but it’s predicted by what’s known as the modified Newtonian dynamics theory, or MOND. “What we’re really saying is that there is absolutely evidence for a discrepancy,” McGaugh said. “What you see is not what you get, if all you know about is Newton and Einstein.”