> Not that it was all that easy to see. The neutrino wave came around two hours before the first photons from the supernova washed over our planet. It lasted no more than a few seconds, yet within that time trillions upon trillions of neutrinos must have passed through the Earth.
Maybe I am misunderstanding things but I thought neutrinos weakly interacted with gravity, thus they possessed a little bit of mass.
Then how can they show up before the first photons from the supernova?
Because photons from the supernova take a few hours to glow through all the mass and dust cloud, like it takes a few hours for the heat to get from the core to the surface and increase the surface brightness and start blowing the star apart. The neutrinos can escape from the core immediately at light speed unhindered.
Apparently, the mean free path for a photon in the sun's core is 0.1mm, and it typically takes about 50,000 years for a photon generated in the core to reach the surface:
Neutrinos have such a hilariously small mass that we are struggling to detect if they travel any slower than light at all, but it is thought that they are slower by an incredibly tiny amount, as in, by somewhere in the range of 1 mile slower per 5000 years. And at this speed, one mile translates to 5 microseconds, which is still nothing compared to the hours it takes for the light from the core of a supernova to push through all the rest of the stellar matter on the way to the surface.
A supernova would therefore need to be about 5 trillion light years away for the photons to catch up to the neutrinos. But the universe isn't even close to being that old or that big, and even if it were, a supernova that far away would be impossible to detect at all.
These extra high energy neutrinos are travelling even closer to the speed of light than average ones. An average neutrino might be travelling at 99.(15 nines)% the speed of light. This one was traveling at 99.(37 nines)% the speed of light.
> Not that it was all that easy to see. The neutrino wave came around two hours before the first photons from the supernova washed over our planet. It lasted no more than a few seconds, yet within that time trillions upon trillions of neutrinos must have passed through the Earth.
Maybe I am misunderstanding things but I thought neutrinos weakly interacted with gravity, thus they possessed a little bit of mass.
Then how can they show up before the first photons from the supernova?
Because photons from the supernova take a few hours to glow through all the mass and dust cloud, like it takes a few hours for the heat to get from the core to the surface and increase the surface brightness and start blowing the star apart. The neutrinos can escape from the core immediately at light speed unhindered.
Apparently, the mean free path for a photon in the sun's core is 0.1mm, and it typically takes about 50,000 years for a photon generated in the core to reach the surface:
https://sunearthday.nasa.gov/2007/locations/ttt_sunlight.php
How can the neutrinos travel at light speed though?
Or is this saying that the neutrinos have such a lead time over the photons that the photons themselves have yet to overcome them?
Neutrinos have such a hilariously small mass that we are struggling to detect if they travel any slower than light at all, but it is thought that they are slower by an incredibly tiny amount, as in, by somewhere in the range of 1 mile slower per 5000 years. And at this speed, one mile translates to 5 microseconds, which is still nothing compared to the hours it takes for the light from the core of a supernova to push through all the rest of the stellar matter on the way to the surface.
A supernova would therefore need to be about 5 trillion light years away for the photons to catch up to the neutrinos. But the universe isn't even close to being that old or that big, and even if it were, a supernova that far away would be impossible to detect at all.
These extra high energy neutrinos are travelling even closer to the speed of light than average ones. An average neutrino might be travelling at 99.(15 nines)% the speed of light. This one was traveling at 99.(37 nines)% the speed of light.