And now you are telling me Galaxies race faster as they get further!!
First, Analogy Time
By chance, if you have to have a huge square elastic sheet of length, let’s say 10 meters. Be a lamb and draw a grid on the elastic sheet. Suppose the grid you draw have a row and column of size 10cm x 10cm. Now, stretch the entire sheet from the extremes and test your strength, just don’t break it.
As the experimenter, now observe. You would simply observe that the size of the row x column has differed subsequently. The catch here is the difference in the scale of rows and columns are not uniform throughout the sheet. The ones that are closer to the center increase the least and the ones that are further, increase the most. It is as if the further the row-column is from the center, the larger it becomes
Distance from the center∝ Increase in its scale
In simple words that doesn’t make much sense before reading the entire story, the more your stretch the sheet, even more it gets stretched. Onwards to the science.
If you don’t know, our universe is expanding, at an accelerating rate. Our universe wasn’t the same as it is today 5 or 7 billion years ago. It would be described as smaller and hotter than the one that we live in today.
But what made it larger and colder??
Edwin Hubble, in 1924 discovered something rather astonishing. Until then, the universe was as small as the 105,700 light years of Milky Way Galaxy. What Hubble changed the perception of our universe. It became 13.8 Billion Years wide. Hubble discovered the universe outside the Milky Way galaxy, distributed with countless more galaxies. Seems pretty obvious today, but wasn’t 100 years ago.
The discovery followed by the observation that these galaxy, anywhere you can find seem to be racing further away from us. This was still not what astonished the academic. The fact that the galaxies that were already further away from us were racing faster than the ones that were close to us.
It was like, the universe was expanding and that too at an accelerating rate.
This turned out to be true supported by the mathematics of General Relativity, Optics and other developments. Foundations of Cosmology was planted that day. The Big Bang Theory, Cosmic Microwave Background, Dark Matter, Dark Energy, Lambda CDM Model and countless other theories unite and make up the Cosmological Standard Model.
But, what exactly did Hubble observe??
In the era where X-Ray Telescopes weren’t a thing and the only thing that astronomers had with them was High Magnitude Telescope with a spectroscope, Paper and a Pen. He wasn’t putting his eye in the eyepiece of the telescope nor was he seeing the images of the sky at different points of time.
After he discovered that Galaxies outside Milky Way exist, he sat down a little longer and collected data, nothing more. The data didn’t match any of the existing model in Physics. The data indicated that each time the telescope collected data about a single galaxy:
Its wavelength decreased. And each time it decreased, the next time it decreased even more and subsequently.
Refer to this story about wavelengths and distances (without math): https://lakshyapratapmonga.medium.com/okay-you-are-telling-me-galaxies-are-racing-faster-as-they-get-further-ffebc3b89a85
Sometimes these wavelengths weren’t even the part of the visible spectrum (which make the 0.0035 % of the entire electromagnetic spectrum). He computed the distances with these wavelengths, “astonishing” was the expression on his face after he discovered:
The universe was expanding at and accelerating rate.
This was one of the biggest discoveries ever in the course of human civilization. Many people followed down the path of becoming Physicists and contributed to the field bringing us closer to have a perfect understand of our universe.
This was the Expansion of the Universe, simply explained.
These discoveries didn’t come without math. And the math behind the waves and distances of galaxies are coming up in the next story, or your curiosity!!
Thanks for reading till here, awesomely high-five 🙌🙌. Have a great day ahead!!
