Pubudu writes:
Mr Fry mentions that neutrinos have no mass when describing how they
travel through pretty much anything. Neutrinos DO have a mass, albeit
very very small.
An Elf replies:
Yes, you're spot on. In Series 4 Episode 12, Stephen did indeed say
"Neutrinos are weird things that go through everything. There are millions literally going through your body now, all the time. They have no mass. They'll go through light-years' thickness of lead just like that, without leaving a trace."
This may well have been true in the Standard Model of the past, but it was shown in 1998 that neutrinos do indeed have a mass. If you google "Neutrino Mass" you will get only "non-zero" in actual fact we don't know what the mass of a neutrino is; all we know is that it's really small and it isn't zero.
So if they're so small, why should we care about their mass? Well the reason is that there's so many of them, so the mass adds up. In fact, neutrinos are sometimes put forward as a candidate for the missing "dark matter," the missing part of the universe that cosmologists are looking for. If they were proved to be responsible, these tiny particles could tell us more about the nature of the Universe than anything else.
Particles are just like quibbles; sometimes the smallest turn out to be the most important.
Quibble Qualified
Do you have a bone to pick with QI? E-mail us here: elves@qi.com
Or watch us tweet at http://twitter.com/qikipedia
Mr Fry mentions that neutrinos have no mass when describing how they
travel through pretty much anything. Neutrinos DO have a mass, albeit
very very small.
An Elf replies:
Yes, you're spot on. In Series 4 Episode 12, Stephen did indeed say
"Neutrinos are weird things that go through everything. There are millions literally going through your body now, all the time. They have no mass. They'll go through light-years' thickness of lead just like that, without leaving a trace."
This may well have been true in the Standard Model of the past, but it was shown in 1998 that neutrinos do indeed have a mass. If you google "Neutrino Mass" you will get only "non-zero" in actual fact we don't know what the mass of a neutrino is; all we know is that it's really small and it isn't zero.
So if they're so small, why should we care about their mass? Well the reason is that there's so many of them, so the mass adds up. In fact, neutrinos are sometimes put forward as a candidate for the missing "dark matter," the missing part of the universe that cosmologists are looking for. If they were proved to be responsible, these tiny particles could tell us more about the nature of the Universe than anything else.
Particles are just like quibbles; sometimes the smallest turn out to be the most important.
Quibble Qualified
Do you have a bone to pick with QI? E-mail us here: elves@qi.com
Or watch us tweet at http://twitter.com/qikipedia
are they the same as or similar to pulsars?
It is not true that more Vietnam veterans committed suicide than died in combat.
http://www.vhfcn.org/stat.html
no pulsars are stars
@ Aida:
Pulsars are a large scale phenomenon involving a rotating neutron star emitting a beam of radiation from their poles, Neutrinos are sub atomic particles.
Hope this clarifies things