How do neutrinos do it?

[freeztar]

I just read the wiki on neutrinos (what I could absorb anyways) and I was left with the basic question of, "How do neutrinos pass through mass seemingly unaffected?".
Speed would seem logical, but not when you consider the fact that neutrinos travel "near" the speed of light and are not affected by the collapse of a massive star, whereas photons are.

Optical photons can be obscured or diffused by dust, gas and background radiation. High-energy cosmic rays, in the form of fast-moving protons and atomic nuclei, are not able to travel more than about 100 megaparsecs due to the GZK cutoff. Neutrinos can travel this distance, and greater distances, with very little attenuation.

Neutrino - Wikipedia, the free encyclopedia

So then I considered mass. And this quote from the same wiki entry threw me off:

In particle physics the main virtue of studying neutrinos is that they are typically the lowest mass...

"Typically"?
This implies that there are other fermions that are sometimes less massive.

Then I just turned to the simple explanation and thought that it must be because they are so small that they pass through atomic structures themselves as if traveling through a multitude of solar systems. But then how come they are not affected by electro-magnetic fields?

I'm stumped.

Does the scientific community have an explanation for "why" neutrinos flow through the earth virtually unimpeded?

[Jay-qu]

They just dont interact. Low mass means not effected by gravity much, no-charge means not effected by electrodynamic forces. That and the fact that atoms are composed largely just of empty space, lets them pass through just about anything uninhibited.

[Erasmus00]

Originally Posted by freeztar

I just read the wiki on neutrinos (what I could absorb anyways) and I was left with the basic question of, "How do neutrinos pass through mass seemingly unaffected?".
Speed would seem logical, but not when you consider the fact that neutrinos travel "near" the speed of light and are not affected by the collapse of a massive star, whereas photons are.

Neutrinos ARE effected by gravity in pretty much the same was photons. The thing that makes neutrinos different is that they don't interact at all with photons, and so other then a direct collision there is no way for any other fermion to mess with them.

The reason photons aren't a great probe for things like stars is that stars are often composed of vast amounts of ionized material. The photons interact and get scattered by these charged particles.

"Typically"?
This implies that there are other fermions that are sometimes less massive.

Neutrinos ARE the least massive fermions, but as you get a particles energy/momentum higher and higher its mass becomes less and less relevant. Hence, sometimes its a good approximation to think of an electron as massless. Its almost always a good approximation to think of a neutrino as massless.

Then I just turned to the simple explanation and thought that it must be because they are so small that they pass through atomic structures themselves as if traveling through a multitude of solar systems. But then how come they are not affected by electro-magnetic fields?

The reason they aren't effected by electro-magnetic fields is quite simple: they are neutral particles. Given that atomic structure is mostly empty space, its pretty unlikely the neutrino can directly collide with another fermion and, being neutral, the electric fields don't mess with it at all.
-Will

[jungjedi]

i think they blink on and off with a strange periocity.like viertual particles,they only have a tendency to exist

[freeztar]

Great replies!
I get it now and reviewing the wiki article, I found this obvious pointer:

Because it is an electrically neutral lepton, the neutrino interacts neither by way of the strong nor the electromagnetic force, but only through the weak force and gravity.

I like the simple eloquence of Jay-q's response and the thoughtful and inspiring (...me to research other aspects of the ideas presented...) post by Erasmus00!

My questions are cleared up for now, but I'm sure I'll have more once I sit on it for a little while.

[freeztar]

Originally Posted by jungjedi

i think they blink on and off with a strange periocity.like viertual particles,they only have a tendency to exist

Can you elaborate?

[jungjedi]

Originally Posted by freeztar

Can you elaborate?

i would really like to.
but first a poem by pablo neruda
March days return with their covert light,
and huge fish swim through the sky,

vague earthly vapours progress in secret,

things slip to silence one by one.



Through fortuity, at this crisis of errant skies,

you reunite the lives of the sea to that of fire,

grey lurchings of the ship of winter

to the form that love carved in the guitar.



O love, O rose soaked by mermaids and spume,

dancing flame that climbs the invisible stairway,

to waken the blood in insomnia’s labyrinth,



so that the waves can complete themselves in the sky,

the sea forget its cargoes and rages,

and the world fall into darkness’s nets.

[jungjedi]

Originally Posted by freeztar

Can you elaborate?

ok,im back,what do you want me to elaborate on.What makes a sea of virtual particles.Howw long they remainin this universe.what makes them blink on and off.i too have so many questions

[freeztar]

Originally Posted by jungjedi

ok,im back,what do you want me to elaborate on.What makes a sea of virtual particles.Howw long they remainin this universe.what makes them blink on and off.i too have so many questions

I don't expect an answer explaining the universe. Rather, I would wish upon an explanation that clarifies the "blinking" of neutrinos. In other words, a credible source documenting this "behavior" would be most appropriate.

PS Neruda Rocks!

[CraigD]

Originally Posted by jungjedi

i think they blink on and off with a strange periocity.like viertual particles,they only have a tendency to exist

To the best of my knowledge, neutrinos are not virtual particles. They don’t blink in and out of existence, or tunnel, more than other leptons, such as the electron.

The do appear to oscillate, shifting through the three “flavors” of neutrinos at they travel. This phenomena has become the leading explanation for the solar neutrino problem, a shortage in the observed number of electron neutrino predicted by particle physics to be produced in greatest numbers by the Sun. Most theorists now accept that we detect too few electron neutrinos, because many of them have oscillated into muon or tau neutrinos by the time they reach Earth. New detectors capable of detecting all 3 neutrino flavors support this explanation, finding muon and tau neutrinos that can only be explained as having been electron neutrinos when they were created by nuclear fusion in the Sun.