Neutrinos Have Mass! (And Not Just on Sunday)

Image courtesy of Argonne National Laboratory

We used to think neutrinos were massless, because from what little we knew about them, they appear to travel at the speed of light. Massive particles cannot do that, because it would take infinite energy to accelerate them that much.

Neutrinos don't interact with matter very much at all. It has been estimated that a ball of lead the size of our solar system would only affect about half of the enormous stream of neutrinos emitted by the sun each second. Those babies fly through everything at nearly the speed of light, as if it were nothing. Consequently, they're very hard to measure.

Somehow, we figured out that neutrinos come in three flavors: electron, muon, and tau. Yeah, whatever. They just do. And yes, particle physicists call them 'flavors'. But recently, scientists discovered that neutrinos can change flavors on the fly. Apparently, this can only happen if neutrinos have mass.

This is the part that mystifies me. All the articles I've read simply say that the ability to change flavors requires (or implies) that neutrinos have mass, but they don't say why. That's understandable, I guess, when the explanation looks like this. I'm going to have to study mass eigenstates for a while, I guess. Yowsa!

Recent experiments have established the maximum range for the mass of a neutrino at about 1eV. This is still a miniscule mass-slash-energy, and neutrinos of such a small mass can still move so fast that for all intents and purposes, they appear to be moving at the speed of light. The difference is negligible, and neutrinos are hard to measure anyway.

It's a strange, strange world, quantum physics is. A great deal of it has been experimentally verified to very high precision, with reproducible regularity. But if you're into weird, you can't make this stuff up.

Space Aliens Cannot Hear Our Radio Broadcasts

Calling Occupants of Interplanetary Craft was a song by Klaatu and popularized by the Carpenters way back in 1975. It explored the idea that we've been broadcasting radio signals for about 100 years, and those signals are now about 100 light years away. The idea being that remote intelligence could be eavesdropping on our goings on by listening to these broadcasts. Classical, jazz, swing, rock'n'roll, The Honeymooners, Lucy, Star Trek, General Hospital, Mary Tyler Moore, Friends, Seinfeld, and so on.

Except none of that is even remotely possible. A spacecraft orbiting our earth might be able to pick up short bursts and squawks, if they knew the details of our modulation schemes. Maybe analog AM and FM would be decipherable, but digital is highly unlikely. What's more, our terrestrial commercial broadcasts are designed for terrestrial pickup. A very small amount of power is accidentally beamed up into the sky, and even less makes it outside of our atmosphere. The ionosphere reflects most of it back to ground. But it gets worse. Anyone outside earth orbit would receive a hodgepodge of signals from all over the planet: nothing but a scramble of noise and interference.

We do beam some signals out to satellites, spacecraft, and once upon a time, to men on or near the moon. But those transmissions are beamed specifically at the target, with tracking antennae. And remember, the earth is spinning on its axis. The radio signals we beam out sweep across the sky as the earth rotates. The farther away it gets, the faster it sweeps. So someone 100 light years away would only get a blip of a single station for a fraction of a second every 24 hours. If they were trying to listen to a conversation, or a newscast, let alone decode our picture format, forget about it. If they could receive us at all, we'd look like a noisy radio source; a pulsar.

Keep in mind that our signals would get weaker and weaker as the beams spread out, the further they get from earth. Besides, there would be natural and alien made interference near the alien's receivers that would drown out our feeble squawkings.

The idea that anyone could actually receive, decode and listen to our stupid broadcasts is absolutely ridiculous. That's why I cannot take anything Carl Sagan says seriously.