# QuestionNeutrinos from the Sun

#### Terra Australis

Has scientific research proven that neutrinos shape change as they head towards Earth? Is this why only one third of the expected number of neutrinos have been detected? How are they able to change type or ‘flavour’ as it is known?

#### Helio

Has scientific research proven that neutrinos shape change as they head towards Earth? Is this why only one third of the expected number of neutrinos have been detected? How are they able to change type or ‘flavour’ as it is known?
There is evidence that neutrinos do indeed change from one type to the next. This is also important because it takes time for any kind of change to occur. Since photons travel in zero time from point A to point B, then neutrinos travel a little slower, thus it is fairly assured they do actually have some very slight mass.

Terra Australis

#### Vincent Peri

...Since photons travel in zero time from point A to point B....
Photons do take time to travel from point A to point B. Just because they're massless doesn't mean they travel instantaneously.

Catastrophe

#### Helio

Photons do take time to travel from point A to point B. Just because they're massless doesn't mean they travel instantaneously.
From our inertial frame, photons, of course, travel at the speed of light, so yes they do take time from our point of view.

But in their own inertial frame, t=0; they travel across the universe without one second ticking off their would-be watches.

Space travelers, approaching the speed of light, would also see time dilation, thus reaching their destination much faster than those on Earth would expect (if they ignore SR - Special Relativity).

This is why in the "Twin Paradox" the traveler returns home to his twin who is now older.

#### Terra Australis

Photons do take time to travel from point A to point B. Just because they're massless doesn't mean they travel instantaneously.
Well established fact that it takes sunlight around 8 minutes to reach the Earth and space distance is measured by the time it takes for light to travel in a year.

#### Terra Australis

There is evidence that neutrinos do indeed change from one type to the next. This is also important because it takes time for any kind of change to occur. Since photons travel in zero time from point A to point B, then neutrinos travel a little slower, thus it is fairly assured they do actually have some very slight mass.
Neutrinos from the Sun have around 8 mins to shape change before they are detected on Earth. My understanding is that there are three flavours of neutrinos electron, tau and muon. There is now evidence that they do have some mass attributed to them and it is this mass that distinguishes between them. How they oscillate between these flavours is still being researched. An interesting question is if a neutrino oscillates from a lower mass neutrino to a higher mass neutrino where is this mass coming from? Is energy being converted into mass?

#### Catastrophe

##### "Science begets knowledge, opinion ignorance.
Hardly interacting with other matter, neutrinos come in the three different types—electron, muon, and tau—and the winners of this year's prize showed that the three types can morph into one another as the particles zip along at near-light speed. That, in turn, proves that the elusive particle must have mass.6 Oct 2015

Proof that neutrinos change identity bags physics Nobel

Cat

#### Terra Australis

So interesting. Especially the part that said if neutrinos travelled at the speed of light it would be impossible for them to change. Therefore they must travel at slightly below light speed and take slightly longer to reach the Earth from the Sun than sunlight. Thank you for your reply Cat.

Catastrophe

#### Helio

Neutrinos from the Sun have around 8 mins to shape change before they are detected on Earth.
Photons also take ~ 8 minutes to reach us, but that is our view of them from our inertial frame, not theirs. What can and cannot happen depends upon the time that takes place in their inertial frame, not ours. This time dilation (SR) is not a question in science. Photons reach us in zero time, neutrinos, however, take some tiny amount of time to reach us, which does allow them to change.

#### Helio

So interesting. Especially the part that said if neutrinos travelled at the speed of light it would be impossible for them to change. Therefore they must travel at slightly below light speed and take slightly longer to reach the Earth from the Sun than sunlight. Thank you for your reply Cat.
Yes, at the speed of light t =0, eliminating the needed requirement to allow change -- time.

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