Einstein hypothesized that the universe is like a flat sheet that runs on forever, deformed by matter such as stars and galaxies. However, scientists continue to question whether the universe really is infinite.
The further away a galaxy or star is from Earth, the older it is. Today, we can see back to a maximum of about 13 billion years ago where there is a space containing the aftershock of the big bang.
This space is filled with gas and plasma so hot that light cannot pass through, forming a layer of cosmic microwave background radiation that is separating us from a possible boundary of the universe.
But regardless of our limited ability to research the space beyond, cosmologists use logic to reason that our universe is finite.
According to the big bang theory, the universe was once a small condensed ball of energy. When it exploded, all the matter and space in that ball expanded outwards, and continues to expand to this day, making it an infinite universe.
However, physicist Andreas Albrecht at University of California, Davis compares the expanding universe to blowing a bubble. He says inflation must stop when space gets to a certain maximum size which he predicts is about 20 percent bigger than its current size.
Cosmologist Neil Cornish at Montana State University agrees that the universe is finite.
“So one problem with an infinite universe—it’s not just infinite in space, but also infinite in time. It has no beginning," he said in a recent episode of Morgan Freeman’s Through the Wormhole.
"You have an infinite number of stars, so the sky would be just completely covered in white," he added. "Bright, bright, so bright that it would fry you.”
However, the stars are actually sparsely distributed in space with darkness all around, contradicting the infinite theory.
‘Only two things are infinite: the universe and human stupidity; and I’m not sure about the the universe.’
So if the universe really is finite, what would it be like?
Jean-Pierre Luminet, a cosmologist at the Paris Observatory, likens the universe to an enormous musical instrument, explaining that the larger a piano, or any other instrument, the greater the range of harmonics that can be heard.
He analyzed vibration ripples in the cosmic microwave backgound and found it is missing the longest wavelengths or "low tones," supporting the theory of a finite universe.
Based on his research, Luminet believes the perfect shape of the universe is a three-dimensional dodecahedron, ie it has 12 sides like a soccer ball.
Cosmologist Janna Levin at Columbia University, New York thinks the boundary of the universe is in the form of a three-dimensional rectangle, comparing it to a spaceship traveling through the universe in a gigantic game of asteroids.
In the game, when the spaceship flies off the screen on one side, it reappears on the screen from the opposite side.In other words, when the spaceship exits the cube through a certain point on the universe’s boundary, it will also be entering the cube through another point, exactly opposite the point the spaceship exited from.
Physicist Glenn Starkman at Case Western Reserve University, Ohio has been examining cosmic microwave background data from the Wilkinson Microwave Anisotrophy (WMAP) Probe, a spacecraft which measures temperature differences in radiant heat remaining from the big bang.
Starkman has been testing out Luminet’s prediction that the universe is dodecahedron-shaped, using the pattern of hot and cold spots detected by WMAP—sound waves that traveled through the universe when it was very young.
He could not find evidence of a 12-sided universe within the cosmic microwave background layer, but is now using a spectrum analyzer and complex mathematical calculations to test whether the shape might exist outside the layer.
These findings present different perspectives on the possible finite nature of our universe, but cosmologists have yet to agree on what form it actually takes.
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