One Universe at a Time

Ten Amazing Things Astrophysics Says About You

Credit: Graham Crumb/Imagicity.com (CC BY-SA 3.0)

1) You live on a rock
Your home is a roughly spherical rock that orbits a star at about 100,000 miles per hour. Most of the surface is covered with a layer of water to produce lakes and oceans, and surrounding it all is a layer of air so thin that if the Earth were the size of an apple the atmosphere would be thinner than the apple’s skin. That’s home, and so far it’s been home for every single human that has ever lived. 

2) You are made of stardust
Sure it’s a bit cliche, but that doesn’t make it any less amazing. The carbon, nitrogen and oxygen in your body was created in the heart of a star long before our solar system formed. The most common elements in your body are also the most common elements in the galaxy. As a result you embody the history of our solar system.

3) Part of you is as old as time
While the heavier elements in your body were created in the hearts of stars, the hydrogen in your body formed about three minutes after the big bang. But the protons in your body formed about a millionth of a second after the big bang. Some of the protons that formed in the earliest moment of the Universe are in your body today.

4) You are the center of the Universe
Often it’s said that the Universe has no center. The big bang didn’t begin a particular point as a great explosion. All of the Universe (even space and time) formed together, which means where you are right now was once at the heart of the big bang. So you really are at the center of the Universe. Of course the same can be said about any other point in the Universe.

5) You are moving at 360 kilometers per second
The Universe is filled with a sea of microwave energy known as the cosmic microwave background (CMB). It is the thermal remnant of the big bang. The wavelengths we see are almost the same in all direction, but interestingly one side of the Universe has slightly longer wavelengths than the other. This is because our solar system is moving through space, causing the CMB to be slightly redshifted behind us and blueshifted ahead of us. It turns out that we are moving through space at about 360 km/s, which is surprisingly fast.

6) You are bombarded by neutrinos
Neutrinos are created in the core of our Sun through nuclear fusion. They are also created in the cores of distant stars. Since neutrinos don’t interact strongly with other matter, they tend to stream through things without interacting. And there are billions upon billions of them. At any given moment there are about 100 billion solar neutrinos streaming through every centimeter of your body. At night they travel through the entire Earth to reach you.

7) You are hotter than the Sun
The Sun has a much higher temperature than you. Even its surface is nearly 6,000 Kelvin, compared to your measly 310 Kelvin. But per volume you generate more heat than the Sun. That’s a bit misleading, since you generate heat through most of your volume through chemical reactions, but the Sun only generates heat in its core through nuclear fusion. Still, it’s a cool fact.

8) Everything is attracted to you
The universal law of gravity states that every mass is attracted to every other mass. When you step on a scale in the morning, the weight you measure is not just your weight in the Earth’s gravitational field, it is also the Earth’s weight in your gravitational field. Gravitationally you are pulling every slightly on everything around you. Everything is gravitationally attracted to you, even though that attraction is usually too small to notice.

9) Your experience of time is unique
Contrary to popular belief there is no cosmic clock that determines time in the Universe. According to relativity, there is no universal “now.” Instead, what constitutes the present depends upon your particular position and motion, and anyone with a different position and motion experiences a slightly different rate of time. You have a “now” that is uniquely yours.

10) There is only one of you
The Universe is mind-bogglingly huge. It’s estimated that there are 100 billion galaxies in the visible universe alone. That’s more than 10 galaxies for every man, woman and child on Earth. Those galaxies might have an average of about 100 billion stars. Around most of those stars might be tens of planets. Despite that vast diversity, the odds of your combination of DNA and your experiences coming together by chance is so astronomically tiny that there can only be one you in the entire cosmos.

The Universe is 93 billion light years across with billions upon billions of potentially habitable worlds, and yet there’s no one else quite like you.