Is the Universe Expanding and What Does That Mean?

Scientists have long ago reached this consensus: the Universe is expanding.

However, as you read this article, nothing gives away the fact that you’re rapidly drifting through and with space. Can you tell that — at this very instant — Earth is rotating at an astonishing speed or that our Galaxy is accelerating? Probably not, but there’s no doubt that space is ballooning.

But what does that mean? And how does the expansion of the Universe influence us?

Grab a raising bun (we’ll tell you why later) and read on to find out how the Universe is expanding and what it all means.

So, is the Universe really expanding?

Yes, there’s no doubt that the Universe is expanding. Ever since the Big Bang, space has been growing and growing.

We know this to be true for over a century now, thanks to astronomer Edwin Hubble. Back in the 1920s, Hubble managed to prove that the Universe is inflating. He did this by showing a connection between the speed of galaxies and their distance from one another.

*Edwin Hubble; image courtesy Mount Wilson and Palomar Observatories

Hubble’s observations shook our understanding of the cosmos to the core. Long before the era of space exploration, he helps us peek into the unknowns of the Universe and grasp its greatness.

As a sign of recognition, the scientific community named the Hubble Space Telescope after him. What do you want to prove one day to earn the trust and respect of the STEM community? Think hard, and get to work!

Okay, but what does it mean?

The fact that the Universe is expanding means that galaxies are moving away from us. Yes, all galaxies are running away from the Milky Way. At the same time, the Milky way is running away from them.

And some galaxies are faster than others. If we take our Milky Way as the reference point, closer galaxies move at a slower pace while those further away move the fastest.

However, what is even more fascinating is that galaxies don’t make their way through space, but with space, in tandem. Space itself is expanding.

*Galaxy captured by the Hubble Telescope; image courtesy of NASA.

Remember that raisin bun we told you to grab? Well, even if you don’t have one close by, think of one. Imagine the dough from which the bun was made, rising. As the dough grew and expanded, what do you think happened with the raisins?

If your answer was “they moved away from each other”, you were right! The same happens with space and galaxies. Put in more delicious, edible terms, our Universe is comparable to a raisin bun. Yum.

But there’s more to this raisin comparison than our sweet tooth. In fact, it holds another essential truth you should remember: the Universe has no centre. Instead, everything moves away from everything. And the speed with which this happens is called the Hubble Constant.

How fast is our Universe expanding?

The Hubble Constant was meant to express the expansion rate of our Universe. Well, it appears this constant is not...constant.

Mind-boggling, we know. But hear this.

In the 1920s, scientists predicted that galaxies will continue to move at a certain average speed. To confirm the calculations, they continued to monitor the location of galaxies through time. But guess what?

Looking at the Universe with Hubble and other telescopes, scientists are now observing that their initial predictions are off. The galaxies are not in the locations they ought to be. They are much farther.

Nobel Prize-winning astronomer Adam Riess even said that “[The universe] is outpacing all our expectations in its expansion, and that is very puzzling.”

The fact that the Universe is expanding faster than we believed it would means we’re missing something. It also means that some of the physics we relied upon might not be accurate. Ultimately, it drives us to once again question everything and start again.

But isn’t this the beauty of science?

Do you love science? Prove it.

If you love science, you’ve landed in the best possible place.

Expand your view on the world and the Universe with our participative STEM programmes — equally fun and educative.

Step into the boots of an astronaut, or simply discover fascinating facts that will help you become a world-renowned scientist.

Because maybe — one day — you’ll figure out what everybody is failing to understand today. What do you think? Will you be the one to solve the secrets behind the Universe's expansion?

We see a glimpse in you, Junior Astronaut. Great things await.

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