The debate on the very nature of our universe, at the cutting edge, has more to do with imagination than with physics, let alone experiments. Which is why the occasion to prove or disprove one of the wild theories describing the universe is very cherished by scientists.One such occasion arose when scientists used NASA's Fermi Gamma-ray Space Telescope to determine whether the universe is smooth or foamy.
The debate is whether the universe, at its very essence is smooth, i.e. continuous, or foamy or bumpy, i.e. with tiny imperfections.
Fermi is designed to detect and measure gamma ray bursts. Recently, it detected such an event happening 7 billion light years away.
Such a remove and relatively small event means that only a very small amount of light arrives at the telescope. In fact, it only detected three photos from the original source.
But they all arrived within a millisecond, indicating that they traveled all that way closely packed together.
The fact that all three flew through 7 billion light years and arrived unaltered is proof, the researchers say, of the smooth nature of the universe.
Albert Einstein was one of the proponents of a smooth universe, in tune with his general dislike of the randomness of quantum physics. Later though, physicists argued for a foamy universe with small imperfections.
These imperfections are at the tiniest of scale, smaller than known subparticles. But the wavelength of gamma ray light is so small that it is comparable to the scale of the proposed imperfections.
If the universe were foamy, the photos would have been affected and scattered all over the place, making it close to impossible for them to travel all that distance unperturbed.
More research is needed of course but, even if the universe is smooth at this scale, it doesn't mean it's smooth at below the Planck length.
The Planck length is generally considered the smallest scale at which anything we know about the universe, the particles we have discovered and the very laws of physics, still works. It's approximately one trillionth of a trillionth the diameter of a hydrogen atom.