MOND experiment cancels all accelerations, could it end dark matter?

William Atkins
Tuesday, 03 April 2007 20:24

Science - Space

Microsoft Office 365

Alexander Ignatiev, from the Theoretical Physics Research Institute (Melbourne, Australia) thinks he can test MOND from two points on the Earth.

MOND, or Modified Newtonian Dynamics, is a theory that explains the rotation of galaxies without the need for dark matter. MOND contradicts Newtonian Dynamics at very small accelerations in the area of a hundred trillionths of a meter per second per second, which is why it is called “Modified” Newtonian Dynamics.

Currently, the dark matter theory about how galaxies rotate assumes that a disc of dark matter exists around each galaxy. This causes all stars within this disc in any particular galaxy to have the same orbital speed.

However, this situation directly contradicts the Newtonian theory of gravity that says objects further out from the center have slower speeds. In our particular case, the outer planets such as Neptune and Uranus orbit the Sun at velocities slower than the inner planets of Mercury and Venus.

Dark matter is believed to exist and evidence has been found to support that contention. Some stars, for instance, travel so fast in their orbits that gravity is not strong enough to keep these stars from falling away and, thus, maintain their orbits. These astrophysicists and cosmologists think dark matter comes into the picture to help gravity control these fast moving stars.
.
However, other scientists are not so sure dark matter exists. They think another explanation is possible—one that involves MOND.

So, Ignatiev is proposing an experiment that would account for all accelerations caused by the motions of the Earth and the Sun. With these accelerations known, a small acceleration might remain, which would prove MOND to be true and dispel the notion of dark matter.

Ignatiev is proposing to set up highly sensitive instruments at two specific latitude and longitude locations on the Earth—one in Antarctica near the south pole and one in northern Greenland near the north pole. And to accurately test his theory he will perform his experiment during the exact moment (with only about a half of one millisecond span of time) of either of one of the equinoxes--the two annual crossings of the equator by the Sun (around March 21 and September 23) when the length of daytime and night-time are equal. These two spots are always at latitudes 79 degrees, 50 minutes above and below the equator, however, the longitudes vary each year.

If his experiment should take place, Ignatiev believes that current instruments could measure the left-over acceleration that would be one hundred-billionth the amount of normal gravitational acceleration at the surface of the Earth.

MOND, first suggested by Israeli physicist Moti Milgrom in 1983, is considered by most cosmologists and astrophysics as a possible but unlikely theory to displace the currently accepted theory of dark matter. (Dark mater is an invisible and yet-to-be-identified matter that does not emit electromagnetic radiation and, supposedly, keeps rotating galaxies from falling apart.)

However, as with any theory, continued investigations and experimentations are needed to prove or disprove whether dark matter or MOND is correct. Right now, we just don’t know.

Research in many areas is being performed concerning the theory of dark matter and Tgnatiev is proposing his idea as written in the March 9, 2007 issue of Physical Review Letters.