Matter/antimatter imbalenc - forked from AMA ask a physicist

[freyar]

that we know if anyway. you mention that sterile neutrinos might be dark matter for all that we know

Yes, though right now we don't know if sterile neutrinos exist.

perhaps for ftl communications for interstellar communications?? *shrug*

Not FTL --- neutinos travel at light speed --- but for SETI a neutrino telescope has an advantage that one detector can see in all directions, since neutrinos pass right through the earth. Or an advanced civilization could use a neutrino beam to communicate through a nebula or something.

The real advantage of neutrino communication is that they can pass through matter, so you could for example communicate with Australia or China from the US without bouncing the signal off a satellite. I looked into it, and people seem a bit excited about the possibility for communication with submarines. It would be very low bandwidth, but submarines already have low bandwidth communications since they have to use extremely low frequency electromagnetic waves that can't be modulated quickly (radio waves can't penetrate water).

re: right handed neutrinos,
if anti neutrinos are sterile neutrinos and ignoring 'the proverbial target' of other mass, and possible other normal matter neutrinos, could this be what anti matter of non neutrino typs are also doing? Maybe it is somehow out of some sort of quantum phase as the rest of the universe? thus able to 'miss' touching any other of matter?

Remember that antimatter particles interact the same was as the corresponding matter particles but with opposite charge. So positrons -- anti-electrons -- interact by electromagnetism just as strongly as electrons do. Also, I might have been a bit confusing in my first post: sterile neutrinos would be some whole new type of particle, not antineutrinos (the antiparticles of neutrinos). We have lots of observations of antineutrinos. You also seem to be thinking about why sterile neutrinos don't feel the electromagnetic, strong, or weak forces. One answer is that they just don't. Of course, there are highly speculative theories that give reasons, like maybe most matter is at one place in extra dimensions and sterile neutrinos are somewhere else. It's not "quantum phase" like sometimes messes up people in Star Trek, but it is kind of out there.

on an aside,
**- [NEW QUESTION ALERT!! BEWARE!!!]-**
I see much talk of such as the electron and positron annihilating each other as with the anti-proton/proton and neutron/anti neutron pairs respectfully, but what if a positron makes contact with a proton?

What Umbran said.

 

[Umbran]

test post for page 4

(okay, something was a little weird, that seemed to make page 4 inaccessible. I'm leaving this no-content post here, in case the problem is with the post above, so the thread has a good post in this page to reach.)

 

[MarkB]

3. Has there been any purpose for these neutrinos as yet - such as the anti-electron has done.

One concept the SF writer Larry Niven used in his novels was "Deep Radar", a RADAR-like detection system using neutrinos, which had the advantage of being able to observe structures deep underground.

I suspect the main difficulty of making such a device practical would be producing a sufficient torrent of neutrinos to get anything like a decent resolution. As mentioned, only a tiny percentage of neutrinos will interact at all with even a planet sized object, and the deep-radar detector would be looking for the several-orders-of-magnitude-smaller percentage of neutrinos that interacted in such a way as to bounce back towards the detector, and then ineracted with the detector itself.

 

[Umbran]

O
I suspect the main difficulty of making such a device practical would be producing a sufficient torrent of neutrinos to get anything like a decent resolution.

The is the problem with any practical use of neutrinos. You need so many of them, and your detector probably needs to be very large, that they become impractical.

 

[Scott DeWar]

Note that "makes contact with" is kind of a misapprehension. We have this idea of "contact", like when we put a hand on a table, and we think that we are really touching, matter to matter. But, on the really small scale, we are not. The electron clouds of my atoms get close to the electron clouds of the table's atoms, and eventually the electric repulsion keeps them apart. Some photons are exchanged to do that, but the electrons never *touch*, per se. The electrons are so close to being mathematical points that the concept of 'touching" is of questionable meaning.

So, we while we tend to speak of them "colliding", really, they get close to each other, and start exchanging force-carrying particles (like photons), until something interesting happens.

In this case, they don't just annihilate into energy, if that's what you are asking. A particle annihilates with its own antiparticle. It isn't a general, "if you are 'antimatter' you annihilate with *anything* that is matter".

I never really thought about that, but it does make sense.

Oh, hey, look, someone has studied this a bit:
https://en.wikipedia.org/wiki/ZEUS_(particle_detector)
http://www.hep.ucl.ac.uk/undergrad-projects/3rdyear/photons-at-HERA/pshera.htm

Squirrel!!

The basic interaction at the energies of these experiments seems to be scattering. They are both positively charged, so getting them close enough to get the positron to go *into* the proton is really hard. Instead, the electrostatic repulsion has them just bounce off each other.

In these interactions, they exchange an energetic photon (that carries the electromagnetic force) in the scattering . Sometimes, that photon is big enough to crack the proton open, and you get a cascade of hadrons* (mostly mesons, I expect). Sometimes, the photon is big enough to produce particle-antiparticle pairs of its own (a meson, in this case), as discussed earlier, and that whams into the proton and you get a cascade of hadrons, slightly different than if the photon did it directly.


*Hadron = particle made of quarks and antiquarks - the proton and neutron are hadrons. There are mesons made of quark-antiquark pairs as well.

thus tthe 'Hadron' of the LHC, I am guessing.

 

[Scott DeWar]

do opposite sides of quark pairs attract each other? such as up/down, does an up quark attract a down quark anywhere like a proton and elecytron pull at each other?

if so, is this the binding force that keeps a nucleus together [protons/neutrons]?

 

[Scott DeWar]

Can you produce neutrinos such as, but not necessarily the same as, an electron is produced in a tube?

then focus the neutrino with a deflector shield array?
sorry about my inner Trekkie

 

[Scott DeWar]

Another question: Are you guys tired of my questions?

 

[Umbran]

Another question: Are you guys tired of my questions?

I will answer this first: No. I like exercising my teaching skills. Ask away!

 

[Scott DeWar]

I will answer this first: No. I like exercising my teaching skills. Ask away!

good!