A (Very) Brief Primer on Black Holes

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John Wheeler was a physicist and National Medal of Science recipient who is credited with coining the term “black hole” in 1967. However, Albert Einstein described it far earlier in a prediction included in his 1915 Theory of General Relativity.

NASA defines a black hole as a place in the universe where the gravitational force is so strong that no light can escape it. Radiation emission is a feature. It was not until 1970 that Stephen Hawking described the life-cycle of a black hole from “birth” to “death”.

Stars and Black Hole Formation

Stars collapse inward when their energy resources are exhausted. This collapse creates a density that increases until an explosion creates a supernova, which is the end of a large star’s life. In turn, supernovas are the primary source of heavy elements (e.g., uranium) in the universe.

The exertional force of the resulting mass of a huge dying star can result in a black hole, which is unable to collapse completely. The reason the existence of black holes was so difficult for scientists to show is that telescopes are designed to observe light, x-rays, and other forms of electromagnetic radiation, so are are not able to reveal black holes.

The following three properties are associated with black holes:

  • Mass;
  • Spin;
  • Electrical charge

A star—which is considered a sun if the center of a planetary system—transforms first into a white dwarf; then into a neutron star; and finally into a black hole. On the other hand, not all dying stars actually transform into black holes.

The Size of Black Holes and their Mass

Mass is the amount of matter (e.g., atoms) in a given object, and black holes are described in terms of mass. For human beings on Earth, the term Body Mass Index (BMI) is the relationship of height to weight. Gravity ensures that our BMIs can be be compared to a normal range as established in medicine.

Black holes most frequently have stars orbiting them. Their mass is typically calculated by measuring the speed of the orbiting material, according to NASA’s Hubblesite. One of the unknown features of black holes is the causal factor that produces their two tremendously different size scales.

Types of Black Holes

The three recognized different types of black holes are:

  1. Miniature black holes – tiny-point explosions;
  2. Stellar black holes – due to huge star collapse;
  3. Super-massive black holes – largest black holes

Einstein’s Contributions as Basis for Hawking’s

Albert Einstein’s relativity theory included space-bending capacity, and black holes demonstrate this mechanism. Per Michael Finkel’s National Geographic report, Einstein did not believe that black holes actually existed. In contrast, Hawking not only showed that they existed, but that black holes could leak energy into space and even explode.

Prior to Hawking’s discoveries, it was believed that black holes could only absorb anything in its gravitational field—but not that it could also explode outward.

Recent Discoveries about Black Holes

In 2016, NuSTAR reported that the XMM-Newton of the European Space Station had documented that a black hole’s gravitational vortex caused material to wobble around it. In that same year, Hawking suggested that mini-black holes could potentially power the Earth with their energy.

Given the need for new global energy sources, this is an exciting idea!