Antimatter isn't dark. Especially when it annihilates.

@Nicho

> Q1 - Where the hell does the 'mass' go ?

Matter is converted into either energy (and by this I mean “converted into photons”), or other types of matter (pions).

> Q2 - What's so special about anti-matter that enables it to unzip ordinary matter into a bazillion massless photons ?

Long story short? There isn’t anything. (In theory.) Antimatter is composed of different fundamental particles, but (in theory) these particles are completely identical to their “regular” counterparts, excepting that the charge/colour/flavour of the given fundamental particle is exactly the opposite of its antiparticle.

Thus when you get a particle and anti particle together they (and I am REALLY simplifying this here) attract eachother with such a powerful force that they obliterate eachother. (Thing car crash.) This particles to convert into other particles.

>Q3 - if everything can be converted to photons then aren't electrons, quarks etc at the same level as atoms ? ie. not really fundamental at all ?

Matter/antimatter collisions don’t produce exclusively photons. A proton/anti-proton reaction actually produces pions indeed of photons. These pions decay about 25% into high-energy photons on the one side and 75% (via a few different routes) into neutrinos on the other.

Remember that a proton and an anti-proton are not in fact annihilating eachother. Instead, the quarks and anti-quarks that are the constituent parts of these larger particles are doing the sub-atomic dance of destruction.

Remember that electrons are leptons; fundamental particles in their own right. So their path to annihilation is actually completely different than protons, as protons are in fact aggregations of quarks.) Each fundamental particle’s interaction with its antiparticle is different than the next.

Even Bosons have antiparticles. The W boson for example has a direct antiparticle (W+ and W- particles). The photon (another boson, just BTW,) also has an anti-particle: itself!

Oh, yeah, didn’t I mention the photon was a particle, not just a quanta of energy? Silly me. But because a photon’s gague symmetry doesn’t break, (i.e. it doesn’t interact with the Higgs field) it doesn’t have a rest mass.

In other words, there are indeed fundamental particles other than photons. Everything does not “convert into photons.” In fact, there are all sorts of ways for particles to convert from one into the other. But each fundamental particle acts completely differently from the other. That’s part of what makes them “fundamental.” They don’t break into smaller ones, and they all have entirely unique behaviours.

@Nicho

"3) Collide matter and anti-matter and you get photons(energy) . They have no mass."

The flaw in your theory is that photons DO have mass. See:

http://hubblesite.org/newscenter/archive/releases/2003/01/image/a/format/web_print/

For more, look up "gravitational lensing" in your favorite search engine. From there, you should be able to track down an easy reference as to why mass and energy are synonymous ... and don't actually "go away", but are converted into another form. Simplistic? Yes, at this level, in under 75 words and an URL. But it works for my nieces & nephews ...

I thought that gravitational lensing worked because the fabric of the universe was curved around the mass, and that the light traveled in straight lines through the curved space, and hence only appeared to be bent (if you're struggling with that, think light travelling through a fibre-optic cable).

@bristolbachelor

You would be correct. But photons do have very small mass due to speed. They have a zero rest mass, however.

@allows comments

I don't see why. Spelling and editing errors, oh my! Embarrassing, really. I have to remember that these forums have no edit feature. Writing from my phone + not using "preview" leads to embarrassment if the comment is larger than the text box.

But…it’s science reporting. More to the point, it’s good science reporting. I can’t not read the comments and participate. Science is why I use the internet at all. Hurrah for science!

Also: yes, I used a double negative. On purpose. For emphasis. Roar!

It is a glorious day...

for SCIENCE! :)

Mass redux

Ok. I know the matter gets converted. My question was how do we go from particles that have mass (quarks and electrons) to particles that have no mass (photons). What is it about anti-matter that causes this to happen with such apparent ease ? If we look at electrons, here we have a particle with mass that can apparently disintigrate when it touches an identical partical with opposite charge. Why does it do that ? Or am i completely missing something important here ..

@BristolBachelor

"I thought"

Dangerous, that ...

"that gravitational lensing worked because the fabric of the universe was curved around the mass, and that the light traveled in straight lines through the curved space, and hence only appeared to be bent."

The gravity of your misconception is staggering ... bottom line: energy is mass. Mass is energy. Both interact with each other.

Curved, bent & straight (etc.) space are figments which attempt to teach TheGreatUnwashed[tm] concepts that they have absolutely no concept of ...

Nope

No mass (according to theory - it'd break gauge symmetry). Momentum, yes (hence radiation pressure), but no mass.

Yarp.

And a neutron star / anti-neutron star collision would produce enough neutrinos to actually be tangible. Scary stuff.

@Trevor

You needn't wait for such a rare event. Type II supernovae explosions are driven* in part by neutrino heating. So many neutrinos are released in the core that their interactions with the shell have a pronounced effect. No doubt if you were close enough you could feel the neutrinos too (for a brief instant before being atomised by the explosion).

Almost all the neutrinos escape of course, to the point at which they can be detected on Earth as in SN1987a. If you want to stress the exponent facility of your calculator, work out the surface area of a sphere radius 168,000 ly, divide it by the cross-section of the three neutrino detectors involved and then again by the probability of neutrino capture. Multiply by 24 (the number detected) and you have an estimate of the number emitted. It's a VERY big number, even by astrophysical standards :) - and SN1987a was an oddly small (for a supernova) explosion.

* At least, according to our best current theories, which are some way from a perfect understanding.

Sir

What I like most about science is that bright people are hell bent on improving our understanding of the universe and our place within it.

What I don't like about science is that very bright people are hell bent on improving our understanding of the universe and our place within it and are letting the morons* ruin our lives within it.

*Politicians for the most part.

Sir

What I don't like about dumb people is that they don't like bright people, becuase it reminds them of how dumb they are, so go on ignoring what they are told by bright people who are hell-bent on trying to improve our understanding of the universe.

Cases in point are 'intelligent design' and anti-global warming proponents, not to mention those responsible for thing like drugs policy who have such a massive aversion to demonstrable facts.

The solution, of course, is in part to ensure that everyone gets a good education, in particularly a strong foundation in maths and the sciences. You have only to look at which nations provide such an education, and which do not to see which are the rising stars, and which are in decline.

However, ID and Anti-AGW people just don't have the ability to recognise how dumb they are, because that bit of brain appears to be missing.

Pity we can't transfer our knowledge, experience and wisdom to new generations more efficiently than continuously having to educate each new generation of potential cave-people from scratch.

One problem with getting a good education is that everyone else becomes relatively more stupid, but quite why people happily boast about being thick, and celebrate ignorance is just beyond me.

Education is absolutely crucial for the future of the whole planet.

AGW is, to some extent, real

Politicians' handling of it, however, is shite.

AGW

The deniers among you really should read the following article:

http://www.bbc.co.uk/news/science-environment-15373071

It is absolutely top notch, and addresses most of the complaints that deniers usually level at climate science.

Tabloids?

It's vastly better than in a lot of the press. Or do you actually prefer the tabloid attitude of writing as if the subject is fully understood by the journalists, when actually they know next to nothing about it and are spouting utter nonsense?

If the author had checked with the wikifiddlers he'd find that

"In physical cosmology, baryogenesis is the generic term for hypothetical physical processes that produced an asymmetry between baryons and antibaryons in the very early universe, resulting in the substantial amounts of residual matter that make up the universe today."

which is what the author thought baryogenesis meant.

Baryogenesis

Sounds like a Dublin Law Firm

This one's actually quite good

I thought Lucy was pretty good and missed her when she left. Lester wasn't a bad substitute but Richard is pretty good. He explains things clearly, lets you know where he thinks he may have a lack of understanding and manages to make readable articles.

And now back to my copy of Scientific American...

Unfortunately...

the article keeps banging on about mass difference e.g " live long enough to measure the positron’s mass" or "one such possibility – that matter and antimatter have different mass."

Sort of....

There are three parts to this*:

1) We don't know whether gravity treats matter and anti-matter identically (eg whether they're identically affected by the Higgs field, or <insert gravitational theory here>)

2) We know that electrons and positrons have very similar masses, but not that they're identical.

3) In a direct annhililation, the tiny fractional differences in mass would be utterly swamped by uncertainties in the measurement (both experimental and fundamental). In the proposed experiment, if the lifetime (and hence beam length) of the positronium can be made sufficiently large, it may be possible to reduce the uncertainties to such an extent that the differences are measurable.

* I don't see how the proposed experiment could disentagle the effects of 1) and 2), but maybe that's why I can only call myself a physicist if I add the prefix 'failed'.

I presume you have peer reviewed evidence to back up your hypothesis? In which journals were they published? Citation?

Is antimatter the mind?

Bugger, every time I try to think of it my thoughts annihilate...