Matt Del Giudice

Extra Credit, #21

Seat G18

April 30, 2000

Detection of Black Holes

The detection of black holes is a scientific issue that has been the impetus for a great deal of current research. Many people question the validity of the claim that black holes are indeed real. To properly understand the detection of black holes, it is first imperative to examine precisely what a black hole is and how it is formed.

Black holes are the evolutionary endpoint of massive stars. “Massive stars” in this sense refers to those stars that are roughly ten to fifteen times as massive as the sun. These stars often experience a death explosion, which results in a rapid increase in luminosity, followed by a gradual period of fading brightness. Such a death explosion is called a supernova. Supernovae leave high amounts of stellar remnant. After the star is engaged as a supernovae, it will collapse to a state of singularity. Singularity becomes the center of the newly formed black hole, where curvature of the spacetime is at its peak. A state of singularity is characterized by the divergence of gravitational tides; thus, no solid object can survive if it hits the singularity. The main reason why a black hole forms is due to the enormous augmentation of density. Light rays gathered get bent and wrap around the star, so no light can escape during this period of “infinite density.” We now have a black hole.

Great amounts of effort have been placed into detecting black holes. The use of x-ray has been suggested as a sensible and efficient method to detect black holes. We cannot see black holes because there is no light that escapes the gravitational field, but we can see their effects on surrounding matter. For instance, if gas from a nearby star were attracted to a black hole, a strong current of gravitational energy would force the gas to a temperature reaching millions of degrees. Because the temperature is so hot, x-rays result. Evidence of detection via x-ray is rather inconclusive and therefore cannot be fully trusted. Scientists have also considered the construction of gravitational wave detectors to provide a viable measurement of the spacetime generated by black holes. Such detectors are not fully perfected, leaving other methods of detection to be used in the meantime.

The Occam’s Razor principle is also relevant in the detection of black holes. It states, “The explanation of any phenomenon that requires the fewest arbitrary assumptions is the most likely to be the correct one.” This principle supports the notion that black hole’s effects on their surroundings can be seen clearly; therefore we have proof they exist. Detection of black holes is most likely to occur when we find an invisible object with a mass that could only possibly demonstrate one. Following the orbit of a companion star can help us attain an unknown mass. If the mass found is greater than three solar masses, it is assumed that a black hole has been discovered. It is clear that scientific theory can be put into practical use with regards to detecting black holes.

References

http://sumer.astro.keele.ac.uk/workx/blackholes/index3.html

www.ncsa.uiuc.edu/cyberia/NumRel/BlackHoleHowSee.html

www.heasarc.gsfc.nasa.gov/docs/objects/objects.html

http://heasarc.gsfc.nasa.gov/docs/objects/binaries/binaries.html