Science trivia

Let me see. I'm a little shaky on this. :eek: They're the next best thing to a black hole, made the same way – a large star, gone supernova. Just not quite dense enough to be a black hole. 'Neutron' star . . . so made mostly of neutrons. Am I close?

(Alpha – helium nucleus, Beta – electron. Question: My science book says a neutron emits an electron to become a proton in beta decay. How does this square with the up-quark and two down-quarks a neutron is made of? Elecrons aren't made of quarks, and even if they were, a neutron doesn't have enough down-quarks to form a -1 charge. I can't figure it out. If anyone knows what on earth is going on here . . . ;))

As for the LHC – I am a physics nerd. :p I don't know nearly as much as I'd like, but I read everything I can get my hands on. For really current stuff I rely on Discover magazine, as that's what our library has . . . and the internet.

What is string theory? (And your opinion of it, if you have one!)
 
Dernhelm said:
Let me see. I'm a little shaky on this. :eek: They're the next best thing to a black hole, made the same way – a large star, gone supernova. Just not quite dense enough to be a black hole. 'Neutron' star . . . so made mostly of neutrons. Am I close?
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Great job! Yeah, actually, astrophysicists are still kinda shaky on this as well-it's still unclear how massive a star needs to be in order to supernova and then become a black hole or neutron star. But we do know that a neutron star is made of neutrons, because matter is packed in so tightly, that all the protons and electrons get squished together, causing trillions of trillions of inverse beta decays which release neutrinos among other things.


(Alpha – helium nucleus, Beta – electron. Question: My science book says a neutron emits an electron to become a proton in beta decay. How does this square with the up-quark and two down-quarks a neutron is made of? Elecrons aren't made of quarks, and even if they were, a neutron doesn't have enough down-quarks to form a -1 charge. I can't figure it out. If anyone knows what on earth is going on here . . . ;))
Click to expand...

good question. As you may know, protons and neutrons are each made of 3 quarks. A proton has 2 "up" quarks (+2/3 charge each) and 1 "down" quark (-1/3 charge) whereas a neutron has 2 downs and one up. What happens in inverse beta decay is that one up quark in the proton converts into a down quark, emitting a "W- vector boson" by the weak interaction. This "W-" boson then decays after a VERY short time (about 10^-25 seconds!!) into an electron and antineutrino.

The Feynman diagram for this process looks like this (which sort of represents what physically happens):

Ibetadecay.gif


(Image: http://www.zamandayolculuk.com/cetinbal/elementaryparticles.htm). I used lots of jargon that you probably haven't heard, but the alternative is that I write a book to explain it! Does that make some sense though??

As for the LHC – I am a physics nerd. :p I don't know nearly as much as I'd like, but I read everything I can get my hands on. For really current stuff I rely on Discover magazine, as that's what our library has . . . and the internet.

What is string theory? (And your opinion of it, if you have one!)
Click to expand...

A theory which may potentially provide the single fundamental principle for physical reality which is needed in order to unify the fundamental forces of nature.

My opinion is that if they're right, then they're spectacularly right and it would probably be the greatest scientific discovery ever. But the whole game is to come up with a unique, observable prediction, of which none has so far been provided and theres not much hope that there will be one in the next century or so. (What are your thoughts??)


Question: What are axions?
 
Wow – I didn't know the answer to this till I looked it up, but I'm answering anyway because the thread will get buried before somebody else gets around to it, I think. :eek: (Hope that's all right with you, Olórin!)

Axion: a hypothetical particle, with zero charge and spin, to fix something called the 'strong CP problem' (lot of math to go through learning about that, looks like. :eek:). Suggested by Peccei and Quinn. Low mass axions could explain dark matter! Photons and axions might turn into one another with the aid of a magnetic field . . . some of the experiments trying to find them are based on this.

Your explanation made great sense, thanks! I don't know quite what a 'W- vector' boson is, but I know all the other stuff.
I guess in regular beta decay (neutron to proton), one of the down-quarks would turn into an up-quark, and emit some kind of boson that would turn into an electron and (?) a neutrino? (I want to say a positron and a neutrino – that would be more symmetric – but beta decay definitely emits electrons.)

On String theory; I agree with you. I've been getting more pessimistic about it after reading Lee Smolin. But it's a wonderful theory . . . and you just can't know. *sigh* I guess there's nothing wrong with assuming it correct 'till proven guilty. :p

Now for a question.

How would a space elevator work, if it could be made?
 
Basically, it would be a huge tower that stretched into space... so that you could launch rockets, satellites, etc. off the top. Maybe it would even have a railgun or some such along the side, so that the rockets could be shot up along it. However, overcoming the tidal forces would be quite an engineering challenge.

Q: How is laser light made?
 
Nicely done on the axion thing, Dernhelm! In my research I might eventually be able to detect axion annihilations in space or oscillations into photons like you said (will probably be at least several years though). And Peccei works at my institution :)

Olórin the Wise said:
Basically, it would be a huge tower that stretched into space... so that you could launch rockets, satellites, etc. off the top. Maybe it would even have a railgun or some such along the side, so that the rockets could be shot up along it. However, overcoming the tidal forces would be quite an engineering challenge.

Q: How is laser light made?
Click to expand...

which kind of laser? a gas laser?
 
Wow! Makes me wish I'd decided to do physics after all. But I wouldn't make it through the math. I'll have to watch the research on that! It sounds wonderful. (Lots of hard work, too, I know.)
 
Light normaly travels straight, so as long as it starts out going in only one direction...it would stay that way.
 
haha, nice job Dernhelm :)

Do you know what atomic orbitals are? (Maybe this can be the "current" trivia question and it can lead into the brief explanation of how lasers work).
 
Yes...at least, I have a basic understanding of the quantum mechanical model, because I'm doing AP Chemistry.

An electron orbital is an area near an atomic nucleus in which a particular electron (or two with -1/2 and 1/2 spin numbers) are most likely to be. Not an orbit as we usually think of one, but a 'probability cloud'. (Heisenburg's Uncertainty Principle)

(Arg. My computer logged me out again . . .)
 
Okay, so here's my simplified (and incomplete) explanation: we know that when electrons in atomic orbitals make transitions between different energy levels, the emit or absorb a photon of a very specific wavelength. Thus, if you have a gas of electrons and excite the electrons to higher energy levels for example by running a current through it-then this will knock some electrons into higher energy levels. But the electrons in the higher energy levels are unstable and will decay back down into lower levels. If you have a bunch of the same kinds of atoms, then as the electrons in the atoms decay back down into the ground state, they will emit photons of a very specific wavelength.

Then inside the laser there is a "cavity," which is mostly reflective, but partially transmittive. So the photons of light produced bounce back and forth many times before they "tunnels" through the end and out of the laser, "stimulating" other atoms to emit more light in the process.

Make any sense?^

Question: when was it discovered that there existed a galaxy outside of our own Milky Way? (Approximate date)
 
Oh, dates. I'm awful at those. Um...anywhere between 1800 - 1900s? I'm pretty sure it was Hubble, but as I said, I can't remember dates. :(
 
Uh...the Milky Way? (I'm assuming that's a trick question :p) Otherwise, Andromeda, which is apparently going to collide with us . . . in about five million years. *hehe* (I like to tell people the first part . . . and then add the timing a bit later. ;))

(Can somebody think of a question? I can't. :confused:)
 
If you count the large and small magellanic clouds as galaxies, then it's those. But the closest "milky way-like" galaxy is andromeda. :)

The answer to my question was around the 1920's-which is astounding when you consider how much more knowledge of the heavens we have since then.

Question: What's the Heisenberg Uncertainty Principle? (have we asked that already? if so, it will be a follow up to a next question...)
 
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