Tag: asteroids

Heinrich Wilhelm Olbers

Wilhelm Olbers was a German astronomer and physician who was born in 1758 and died in 1840. Olbers’ had several noteworthy contributions to the field of astronomy including developing a method to calculate the parabolic orbit of comets. Olbers’ primary focus was in searching for comets. According to Encylopedia Britannica a comet is ” a small body orbiting the sun with a substantial fraction of its composition made up of volatile ices.”

Olbers’ was the first to propose that a comet’s tail is always pointed away from the sun as a result of radiation pressure from the sun itself. Olbers’ is also credited with discovering a total of 5 comets as well as two asteroids, Pallas and Vesta. On March 6th, 1815 Olbers’ discovered a comet with a period of approximately 72 years. The period of the comet was calculated by his friend and colleague Carl Friedrich Gauss and verified by other astronomers of the time. Olbers comet, 13P/Olbers, next perihelion, which is its closet proximity to the sun, will be on June 6th, 2024.

A Scientific Paradox

A paradox, according to Merriam-Webster, is “a statement that is seemingly contradictory or opposed to common sense and yet is perhaps true.” Science is certainly not immune to experiencing a paradox. One of the most famous paradoxes is the grandfather paradox which appears to be a way for nature to forbid time travel to the past. It goes like this, suppose you go back in time and murder your grandfather before he and your grandmother conceive your father. By doing this your father and consequently, you will not be born. If you are not born then you could not have gone back in time to murder your grandfather so then you will be born. A resolution to this paradox is that if you kill your grandfather, you are actually killing him in different universe. Another possible resolution is based on quantum mechanics and the superposition of states. You can watch a short video from minute physics to see the description of the grandfather paradox and possible resolutions to the paradox. https://www.youtube.com/watch?v=XayNKY944lY This is just one example of a paradox in science there are many others you can find by executing a quick google search.

Olber’s Paradox

In 1826 Heinrich Wilhelm Olbers asked a deceptively simple question which became known as Olber’s Paradox. That question was “why is the night sky dark?” If the universe is both endless and populated with bright stars then the night sky should be blindingly bright at least as bright as the sun because every single line of sight must end at a star. If the universe is infinite then we should be able to see a star in every direction. Even if some stars that were further away were dimmer there would be more of them so the result should be a consistent luminosity across the sky.

So why isn’t the night sky uniformly bright?

Perhaps the most reasonable factor in the resolution to Olber’s paradox is that the universe is finite and that light from stars that are more than 13.7 billion years old are to far away for their light to have reached us yet. A second factor is that because the universe is not static but rather is expanding, light from distant galaxies is red-shifted into the non visible portion of the electromagnetic spectrum. The farther away a galaxy is from the earth the higher the red-shift of the visible light. So light from galaxies that are past a certain distance from us is red-shifted to the infrared portion of the spectrum which we can’t detect with our eyes. In summary, because the universe had a beginning, there aren’t stars in every direction, light from stars that are older than 13.7 billion years old hasn’t reached us yet, and because of the expansion of the universe resulting in red-shifting of visible light the night sky looks dark.