Gravity playing tag with Light

In the article, “Gravity may have chased light in the early universe“, by Michael Brooks from, talks about a theory from Joao Magueijo that proposes that the speed of light was different during the big bang. This theory was made to solve the horizon problem. The horizon problem confuses astronomers because the size of the universe is nearly 28 billion light years long but the universe was created around 14 billion years ago. And the radiation can be seen everywhere in the universe but nothing can be faster than light. But now, Joao Magueijo and Niayesh Afshordi have created a new version of the theory, and this one is testable. They suggest that in the early universe, light and gravity propagated at different speeds.

This article relates to our conceptual objective, “I can explain how astronomers know that the universe is expanding and how they determine the age of the universe”, because this article explains that the universe is expanding and tells us how the light from the big bang can be measured. The cosmologist from the article are trying to figure out why the heat distribution is further than light even when nothing in the universe is faster than light. We are able to determine that the universe is expanding through Hubble’s law. Hubble’s law states that the further the galaxy is, the faster its moving away from us. All galaxies are moving away from us. In class, Mr. Morrison demonstrated this law by drawing dots on a piece of paper and overlapping a dot with another paper with the same dots but separated at the same distance. The closes dots appeared to move less distance compared to the further dots that move a greater distance.

Image result for hubble's law expansion

Astronomers are able to determine the age of the universe by either finding the expansion rate of the universe known as Hubble’s constant or studying the oldest objects in the universe. Once astronomers find the expansion rate they can just use it backwards to determine when the big bang first happened. Quasars are the brightest and most distant objects in the universe and by studying the distance of these we can determine the age of the universe. When studying light from the early universe astronomers must use radio waves since they are the longest wave length meaning the furthest distances can be measured using that type of wavelength. The age of the universe is roughly 14 billion years old.

This conceptual object was by far my favorite one to learn about. I’ve never knew that Quasars had supermassive black holes basically giving them the energy to produce all that light. After reading the article, I’ve became more interested in this horizon problem and read more into it. With the information given about the horizon problem I can see why people would back up the theory of light and gravity had different speeds back then. I’ve always knew the universe was expanding but never knew it is expanding at such an extreme rate. I’m grateful of learning all this material learning more and more about the vast universe and objects in it, but this is our last conceptual objective and this class will be missed.


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