Tuesday, May 28, 2019

They Are Building A Neutrino Telescope At The Bottom Of The Mediterranean Sea

This neutrino telescope isn't just at the bottom of the sea. It's looking down, not up.
Deep under the Mediterranean Sea, hundreds of watchful eyes hang suspended on cables, waiting for a rare and valuable flash. Their quarry are ghostly neutrino particles, capable of tunneling through light-years of space and a planet’s worth of rock without ever coming into contact with matter. 
But, here, under the ocean, they just might hit a detector from the Cubic Kilometre Neutrino Telescope, or KM3NeT. While the international collaboration is still in the early stages of construction, it hopes to soon begin tracking some of the most elusive particles in the universe. 
Neutrinos are nearly massless particles produced in the sun and in energetic events like supernovas, colliding stars, and gamma-ray bursts. Because the particles barely interact with the rest of the universe, they are notoriously difficult to study, though trillions pass through your body every second. 
Researchers have tended to bury neutrino detectors in vats of supercooled liquids or miles underground, hoping that neutrinos will be the only particles that make it through.
This time, researchers are hiding the detectors at the bottom of the sea, on the other side of the planet from the skies they hope to study, to block everything but neutrinos from hitting their detectors.
From here (emphasis added).

For what it is worth, at this moment in time, I think that innovative big telescopes (like this one and the new gravitational wave telescopes) are a better investment to answer the solvable questions about the fundamental laws of physics that we haven't solved yet than a new particle accelerator that is seven to twelve times as big as the biggest one we've built yet.

Someday, the time may be ripe to build a new accelerator. But, we can almost guarantee that we won't find anything really revolutionary by increasing the energy scale of the collisions by one order of magnitude. We'd have been getting hints via indirect indications, albeit inconclusive, of what is going on at higher energies already if that was going to happen. But, we haven't been seeing that.

In contrast, we know for a fact that it takes some sort of new physics to explain dark matter and dark energy phenomena, and we have very good reason to think that new data can tell us more about neutrinos and the history of the universe (i.e. cosmology). And, we are getting so much new data, simultaneously, from so many independent sources of new observations, that we actually are making progress on those questions, even though it may not alway seem like that on a day to day basis.


neo said...

"Someday, the time may be ripe to build a new accelerator. But, we can almost guarantee that we won't find anything really revolutionary by increasing the energy scale of the collisions by one order of magnitude."

the price tag for HE-LHC, doubling 14TEV -> 27TEV is about $7 billion around 2030 timeframe, if CERN greenlights this

andrew said...

Yup. Too much money for too little return.

Maybe one could retrofit the LHC from its current proton collider configuration to a lepton collider on the cheap to wring some more precision out of electroweak physics. But, LHC at twice the energy is just not worth $7 billion compared to the value that alternatives could generate.

Even the 100 TeV International Linear Collider (ILC) proposal at seven times the energy and a somewhat different configuration is still not worth many billions of dollars.

Now, I suppose it does depend upon what you are comparing it to. Maybe the marginal benefit of a collider at that cost is a better deal than a couple of new battleships or an aircraft carrier or a squadron of long range bombers in the U.S.'s already flush portfolio of military hardware at comparable prices.

But, compared to other scientific research uses of those funds, it is hard to see, e.g., $7 billion for a bigger collider being worth more than what you could buy in terms of space satellites or gravity wave detectors, e.g., with that kind of money.