Science is not a compilation of a few isolated minds with grandiose ideas, but rather an accumulation of the work of many scientists, working independently, over decades or centuries. Black holes are a strong example of such a scientific struggle. Because they cannot be seen, science argued their very existence from the 1600s until man landed on the moon in 1969.
The saying, “What goes up, must come down,” seems to rule our daily lives. Even the strongest athletes cannot throw something up so fast that it does not eventually come down. Scientists, however, wondered if it was possible to move something so fast that it would escape Earth’s gravity.
With Sir Isaac Newton’s creation of calculus he was able to use his new math to demonstrate that any object could escape gravity if it was going fast enough. In the 1660s he calculated that an object fired in the air would need a starting velocity of 25,000 mph to escape earth’s gravity. Two hundred and fifty years later, Edwin Hubble used observation to prove the correctness of Newton’s calculations.
For 40 years scientists agreed that light’s infinite speed would allow it to escape any gravitational force. Edmond Halley and John Mitchell, however, disagreed. They had observed that stars seemed to be orbiting something that could not be seen. Clearly, they argued, there must be something so massive that nothing could escape its gravity, even light, explaining why it wasn’t visible. They argued that one did not have to see something directly to know it was there; just as one would know someone had been on a beach even if one could not see them by the footprints they left — the orbiting stars being the footprints.
The scientific community disregarded Halley and Mitchell for the next century; they believed that light had infinite speed enabling it to escape any amount of gravity.
In the 1800s, light’s speed was calculated, proving it was not infinite. About 100 years later, Einstein theorized that light had a fixed speed that everything could be measured against; this was his theory of relativity. If light had a finite speed, then enough gravity would prevent light from escaping. An object with enough gravity would be invisible, but could be detected by the orbit of items around it, just as Halley and Mitchell had argued over a century earlier. Over the last 150 years, additional observational and mathematical evidence confirmed and expanded upon these ideas.
Contrary to science fiction and popular belief, black holes do not gallivant around the universe, consuming people, planets, airplanes and stars alike, but, rather, remain where they are. If our sun were to form a black hole, Earth would be in no danger (although humans would, since the lack of heat, light and energy would kill us very quickly), but would continue orbiting like usual, along with every other planet in our solar system.
The only difference would be that the light from the sun (now a black hole) would no longer escape, meaning that no other body outside the black hole’s gravitational field would be visible. Were something previously not in its gravitational pull to enter the black hole (a comet, asteroid, star, etc.); it would never be seen again. What occurs inside the black hole is a complete mystery, with nothing but loose, poorly supported theories to answer the question: an enduring challenge for future generations of physicists worldwide.
The process of science was best described when Sir Isaac Newton, following his recognition for many scientific achievements, explained, “I can only see so far, because I stand upon the shoulders of giants.” His statement acknowledged that science is slowly developed over many centuries by the contributions, both large and small, of many different independently working scientists. Even the greatest scientist could make little progress without the assistance of previous scientific achievement.
