7 Things You Didn’t Know About the Universe
The Universe is an infinite puzzle composed of paradoxes, contradictions, enigmas and anomalies — all of which can be analyzed and understood when you examine them closely. Here are just a few to ponder the next time you look up into the night sky.
1. Think We’re the Only Life Form in the Universe? Think again.
We live on a backwater planet in an unimportant galaxy, illuminated and warmed by a yellow dwarf star, one of the 200 billion stars in the Milky Way — just one of a few hundred billion galaxies in the observable universe. Astronomers now believe that most of the stars in our galaxy have planets orbiting them. We detect these “exoplanets” by observing the slight dimming of a star as a planet crosses in front of it, as seen from Earth.
It’s estimated that about 20% of those planets are orbiting in the sweet spot from their star and could potentially support life. This means that our galaxy contains 20% of 200 billion or 40 billion potentially habitable planets. Surely, some of these have intelligent life. Why haven’t we been contacted by these beings? Or have we?
2. It’s Impossible to Travel to Even the Nearest Star
The distances in the universe are completely unfathomable. We can easily calculate the numbers of miles, feet or meters between objects in interstellar space, but there’s no way for us to really grasp what the distances mean.
Our nearest neighboring star, Proxima Centuri, is about 4.2 light years from us. The greatest velocity that any unmanned rocket so far created will travel at is 430,000 mph. That’s 119 mile per second. How long would it take for a rocket to reach the nearest star? Longer than human beings have existed.
3. The Present is Really the Past
When we look into the night sky, we are looking into the past because the light from the stars has been traveling towards us for billions of years. Which is why we can never know if those stars still exist. When we look at each other, even from close distances, we also see the other person in the past because it takes light a finite time to travel from their bodies to our eyes.
But consider that it takes light nearly a second to reach the moon from the earth. So, we are always looking at the moon more than a second in the past. It takes approximately eight minutes for light to get from the sun to the earth, so if the sun exploded, that information would not reach us for eight minutes.
4. Gravity Slows the Passage of Time
Einstein proved that time runs slower in a gravitational field than it does in empty space. Every chunk of matter creates its own gravitational field, which slows time in its vicinity. So, the earth’s gravitational field slows time around it. Every being on our planet has lived in slow time since the birth of humanity.
A clock on the surface of the earth runs slightly slower than an identical clock on a mountaintop or in a spacecraft. If you live at sea level, and your twin sibling lives on the top of a mountain, he or she will get older slightly faster than you will.
5. Black Holes Can Stop Time
Black holes are bodies with gravitational fields immensely greater than those of the earth or even the sun. A black hole is created when a star uses up its nuclear fuel and collapses. If the star was large enough, its collapse will continue until the dying star becomes a dimensionless point of infinite density: a black hole. Astronomers now think that black holes exist at the center of most galaxies.
If we were to approach a black hole, our clocks would run increasingly slower until they would finally stop at a certain distance from the black hole known as the “event horizon” — a point in space where time no longer exists
6. The Multiverse Consists of an Almost Infinite Number of Universes
String Theory proposes that we actually live in 11-dimensional space, with a very large number of possible arrangements for the hidden dimensions. According to the theory, each arrangement creates a different universe. The number of possible universes is 10 to the 500th power, of which our universe is only one.
The laws of physics will vary widely among these different universes. Other universes may have no stars or galaxies in them. Still others may be on fire. With that many universes, there will probably be exact copies of our own — but possibly with differing histories and evolutionary outcomes.
7. The Stars Will Disappear from the Sky
The universe is constantly expanding. The curious thing about that expansion is that the further objects are from us, the faster they are receding. To better understand this, imagine a balloon on which someone has painted regularly spaced dots. As the balloon inflates, the spots move further away from each other.
The astrophysicist Dr. Brian Greene tells us that we live in a very privileged age, because we can look into the night sky and see trillions of stars. In the future as the expansion drives everything away from each other — including the stars — astronomers will look into the night sky and see stars only blackness. The expansion of the universe will have pulled the stars beyond our view.
