What is Digg?63 Comments
- Grimdotdotdot, on 10/12/2007, -3/+52"Funny. Now beam up my clothes, too."
- chaosmachine, on 10/12/2007, -3/+24chocolate chips.
- shimavak, on 10/12/2007, -0/+18Okay, I'll bite.
We have a very nebulous definition of matter here, so I'll define it in terms of more clear properties: the matter property of any particular particle is defined by its mass.
No inertial mass may move at the speed of light, less it becomes infinitely inertially massive (and requires an infinite amount of force to cause it to accelerate). Thus, any object traveling at the speed of light must necessarily have zero inertial mass. Another way to think of inertial mass, then, is to consider it as the resistance an object has to a force applied to it. As the energy of the object increases, so too must its inertial mass.
What is terribly interesting is how this could apply to photons which--as we've established--are both traveling at the speed of light and massless. It turns out that the wavelength changes, or that electromagnetic fields are more rapidly oscillating, or however you would like to think of it.
The interesting bit is that this is by far not the first time we've observed light creating matter. That is what pair production is all about. Gamma ray comes along, enters a region of high field density, and the energy density becomes so large that it literally rips an electron-positron pair from the vacuum. The gamma ray is lost to these two, they march along their merry way until they meet their own fate at the hands on their respective antiparticles (eachother!); after which a happy gamma ray or two (or three) come out. Why two or three? Well, you have to conserve angular momentum!! And though the photon is massless, it does have an intrinsic spin angular momentum of 1, so you have to have at least two to get the appropriate amount of spin.
Look up Feinmann diagrams if you're interested. The really neat thing is when you consider just what it means for the electron and positron to have annihilated. The way Feinmann saw it, they didn't annihilate, but rather the electron stopped going forward in time and switched to a positron, going backward in time. Thus, the reason that all electrons have the same mass is that they are all the same electron, just zipping through the universe in all four dimensions. The article doesn't nearly go into the fun depth that is out there.
Enjoy - brianpeiris, on 10/12/2007, -0/+16Looks like this is the first time they've observed the phenomenon that has been kicked around in theory.
Although I'm also confused as to why the article doesn't really make a big deal of it. I suppose it's just a preliminary report though.
Also, considering they first found the star more than 7 years ago (http://www.noao.edu/outreach/press/pr01/pr0112.html ), I don't think we're going to hear about any more details for a while.
It's pretty awesome, regardless, it is one of only two star that emit Very High Energy gamma rays. (http://www.sciencedaily.com/releases/2006/05/060519102625.htm ) - edzieba, on 10/12/2007, -4/+19If you have plants that can absorb high energy gamma radiation and turn it into matter, then I've got a bunch of nuclear physicists why might be interested in taking up horticulture.
- shimavak, on 10/12/2007, -1/+13If you're curious, see my comment way down the page. Light going to matter is nothing new; what is new is the analysis which has determined that this is what is going on in these jets. For those curious, the threshold for creating electron-positron pairs from a gamma ray is 1.022 MeV. For those unaware, the difference between a gamma ray and an x-ray are their origins. One is created by slamming electrons into a heavy target to create bremsstrahlung (or braking radiation) photons. The energy of the photons is directly related to the energy of the incoming electrons. Thus, electrons accelerated through a 1,000,000 V potential difference (1 MV) will have an energy of 1 MeV (1 Mega-electron-Volt). So, to reliably produce photons with sufficient energy to create electron positron pairs, you would have to have at least 1.022 MeV electrons.
For those unaware, the most common medical physics accelerators used in radiation oncology (killing cancer with radiation) go all the way up to 18 MV photons! In fact, pair production plays a huge role in the consideration of delivered dose! There are also a good many nuclear decay chains which produce photons with high enough energy to produce electron-positron pairs.
All in all, it is a nice article that could do with quite a bit more explanation. - cmiller1, on 10/12/2007, -4/+15then what matter were those stars composed of?
- mikemac, on 10/12/2007, -0/+9Number-cruching time!
E = m * c^2
c^2 is the speed of light squared, or 8.98755179 × 10^16 (Google)
The mass of a hydrogen atom (smallest atom known to be possible) is 1.67 × 10^-27 kg
This leads us to an energy of 1.50 x 10^-10 Joules required to make a single hydrogen atom (assuming no energy loss in conversion)
The minimum energy of a gamma ray is 124 keV (Wikipedia: Electromagnetic spectrum), or 1.98669881 × 10-14 joules. So we're off by a factor of 1,000.
1.50 × 10^-10 joules is approximately equivalent to 936 MeV, or completely off-the-scale of our little EM band image on the Wikipedia page referenced above. There is no known upper limit to the EM Band, but to follow this along a bit further...
For electromagnetic radiation, E = hf (or f = E/h)
E (Joules)
h (Planck's Constant, 6.626069 × 10^-34)
f (frequency, in Hz)
1.50 × 10^-10 / 6.626069 × 10^-34 = f (Hz)
= 2.26 × 10^23
This is 0.226 Yottahertz, just for reference.
The wavelength of this ray, you may ask? Well, that's λ = c / f.
3.00 × 10^8 / 2.26 × 10^23 = 1.33 × 10^-15 m, or 1.33 femtometers.
That's some high-energy *****. - Kerwin, on 10/12/2007, -11/+19Matter from light you say?
SCOTTY! BEAM ME THE ***** UP! - cmiller1, on 10/12/2007, -2/+10not quite, they are just using light energy to bond together preexisting matter into useful new compounds.
- crweaks23, on 10/12/2007, -0/+5That's a lot to write down. Just do the math in your head.
- Pic0, on 10/12/2007, -3/+8how?
- CaesarBlue, on 10/12/2007, -0/+442 ....
In other news I never knew there where so many rocket scientists and nuclear physicists on digg. Interesting story and all, but does anybody else thing digg hasn't been that great today? - mynameistim, on 10/12/2007, -0/+4we all have our good days and our bad days.
- cmiller1, on 10/12/2007, -1/+5If eventually this can be harnessed for our own use, and energy can be turned into matter of any sort (and objects of any sort through nano construction.) Will energy become the one and only commodity with any value?
- ABadInAlbany, on 10/12/2007, -1/+4idiots are harmful to the body. I wonder if you're close enough to affect me.
our atmosphere and magnetic fields protect us from most extraterrestrial high energy radiation. - borg359, on 10/12/2007, -0/+3@shimavak
The only difference between gamma-rays and x-rays is their energy, not where they come from. They are both forms of electromagnetic radiation, it's just that gamma-rays have a higher frequency. Furthermore, there are plenty of ways to create x-rays, bremsstrahlung radiation just being one of many. Anything hot enough will emit photons in the x-ray spectrum.
Anyway, what these guys found is nothing new. Anytime you have a lot of photons above 1.022 MeV (~10E16 GHz), you have a finite probability that the photons will turn into an electron-positron pairs and hence turn into matter. What's new is that they have successfully determined that particle annihilation is causing the observed x-rays and gamma-rays. The title is a bit sensational if you ask me. - YumYumKittyLoaf, on 10/12/2007, -1/+4One question, was this known before or not? Because if it was just discovered, then that's great (yes I read the article, but I might be a little confused on whether this is new information or just an event we haven't witnessed before but is expected to happen)
- mynameistim, on 10/12/2007, -0/+2thank god that's not true.
it's not true...right? - archlich, on 10/12/2007, -1/+3The problem with creating matter from energy, is that it takes an incredible amount of energy to create it, E=mc^2. So to create the amount of matter it for a few kilograms of uranium will take the amount of energy of an atomic blast.
Also, most matter above iron has been created in neutron star collisions, so it's really really, really, hard to get all that energy back into one place again. (other than at particle accelerators of course) - shimavak, on 10/12/2007, -0/+2@borg359
It really depends heavily on how you define X-ray vs. Gamma-ray photons. I have always heard them defined and referred to as follows: X-ray photons are generated by energetic electron processes, gamma rays by transitions within atomic nuclei.
By the way, radiation from a heated solid (a.k.a. blackbody radiation) IS bremsstrahlung radiation! The electrons in the heated solid have a great amount of kinetic energy, they bounce around, their random velocities are determined by their temperature. As they bounce, they must accelerate! Bremsstrahlung radiation simply results from the application of relativistic electrodynamics to electronic motions. In heated solids it produces blackbody radiation; in monoenergetic electron beams striking a tungsten target, it produces relatively monoenergetic photons. - thisissayantan, on 10/12/2007, -0/+2Interesting... Is this the first natural evidence proving Einstein's mass-energy equivalence equation?
One can't help but admire the genius of Albert Einstein-- he figured all this out with pen and paper. - bart9h, on 10/12/2007, -0/+1Bah, he was just stonned.
I see those all the time.. - Katsushiro, on 10/12/2007, -0/+2Actually, I think he's talking about Hawking's Radiation, which is a different thing altogether, where black holes actually eject certain amounts of matter due to some very odd physical principles.. you can read up about it here:
http://www.fnal.gov/pub/inquiring/questions/blackholerotation.html - OrangeCrush, on 10/12/2007, -1/+2Energy and Matter are made out of the same "stuff" and can readily be converted back and forth. As for "harnessing" this . . . well, you need to get the energy from *somewhere* and the likely sources for that much juice are probably converting some matter into energy to begin with--(i.e. nuclear). Why would we want to convert that energy back into matter? Transmuting one element into another will in many cases be more trouble than it's worth. Sure, we can fuse Hydrogen all the way up to Iron, but it's a lot easier to dig some out of the ground.
- atb12688, on 10/12/2007, -0/+1Star Trek transporters here we come!
- ABadInAlbany, on 10/12/2007, -1/+2isn't it already? economy and trade are really just matters of converting energy into matter, though maybe a little less directly than this gamma ray process.
- shimavak, on 10/12/2007, -0/+1I should probably just add, for pure curiosity, that you are terribly unlikely to be able to heat solids hot enough to achieve a reasonable amount of x-ray emission. Part of the reason for this is that x-rays tend to be somewhere in the energy region of K-shell transitions. If you are generating a lot of electrons with that much energy, they will not be bound very well at all to the material. You'll literally start boiling off electrons at a huge rate, resulting in net ionization of the sample. It will eventually (and likely quite quickly) blow itself apart. You're, of course, going to see some from heated plasmas, but that is about the only thing.
Consider that the ionization potential (tables on wikipaedia) for a few metals (converted from kJ/mol to eV/atom--~0.0104 (eV/atom)/(kJ/mol)) and you'll quickly see that most first ionization potentials are around a few, to tens of eV. The bottom of the listed range for low energy x-rays is about 124 eV (10nm), so we're talking a significant amount of ionization. You're definitely going to be generating x-rays, but it won't be very easy to work with. For a clear picture, that would correspond to a temperature of about 2.9*10^5 K. You'll have a highly ionized material, to be sure. - OrangeCrush, on 10/12/2007, -1/+1@abadincrotch: No. The only matter/energy conversions that occur on planet earth are nuclear or in a particle accelerator. Most of the worlds economy runs on *changing* matter and energy into different forms. When you're doing chemistry, all of the matter remains matter, and all of the energy remains energy. i.e. trees weigh exactly the same as the water, air and soil they've absorbed.
@archlich
Actually, the energy released by a nuclear bomb isn't nearly enough for *kilograms* of uranium. All that energy came from a much smaller amount of uranium actually being annihilated. - TomFrost, on 10/12/2007, -0/+1While that's an interesting idea, JJsays, there's a lot you're not taking into consideration. Read up on waves, and how they cause an interference pattern when two waves of the same frequency collide, changing their phase. When matter collides, force is applied and energy is transferred.
Yet, when a beam of light is split and collides with itself, it does not bounce or exert force on itself. It creates a wave interference pattern. Not at all matter, in this case. - inactive, on 10/12/2007, -0/+1I don't know what the hell you two are going back and forth about but it sounds awesome!
- mmeads, on 10/12/2007, -0/+1darn discovery.com links
http://dsc.discovery.com/news/2006/11/28/rumpelstiltskin_spa_print.html - fitchmicah, on 10/12/2007, -0/+1black holes do something similar to this too I think
- CaesarBlue, on 10/12/2007, -0/+1*think not thing.
- starsky25, on 10/12/2007, -0/+1there is a third type of material that scientists think can be classified as fundamental: information content. there is also an idea called "active information" that behaves as a regulator for what matter and energy conversions.
its a floating theory, but it makes sense that you need all three to specify how a system behaves. - archlich, on 10/12/2007, -1/+2Yes, I realize this, but I wanted to keep my point simple =P
- krinthekuz, on 09/16/2008, -5/+5god hasn't been disproved, but this is another little thing going against him. then again, the zealots will turn around with backwards logic and say "all these phenomena are so complex, that they must be proof of some designer of a greater being!"
- XStatic, on 10/12/2007, -1/+1Light is matter whose fundamental particles "strings" have the harmonic resonance necessary for light speed.
The "big bang" was equivalent to the Tacoma Narrows Bridge disintegrating from sympathetic vibrations and much of the light became matter in a short period of time. - mikemac, on 10/12/2007, -1/+1Black holes do the opposite, I believe; take matter, pretty much obliterate it and release energy in the form of X-Rays that are pretty much the only way to see them.
- DeadWisdom, on 10/12/2007, -2/+2I'll go you one better: when energy is super-abundant and matter is easily created, design and space are the only commodities. Look at Second Life for example.
- chrisklapp, on 10/12/2007, -1/+1
soon to be released...
Armageddon 2
This time its a nearby black hole that grows close enough to rip the earth apart - lessthan15, on 10/12/2007, -0/+0now i don't really know much about it, (obviously i come here to learn it eh?) but that's definitely something i've heard before, although the methods for doing it were unclear.
something i just realized... if we attempted to make all the energy in the universe into matter, it would never work, there would always be just enough left to turn some of the matter back into energy, it is impossible to have an energy-less universe...
and this in no way dissproves the existence of god. (dont' hate me for saying it pleez...) - Wasyu, on 10/12/2007, -0/+0Umm it's almost like a natural replicator.
- shimavak, on 10/12/2007, -0/+0@borg359
Of course, this is absolutely true. Most interesting is that eventually, just as the constituents of the plasma started being stripped of their electrons to get the ever higher energy photons, they will eventually be reduced to a bare nucleus. Eventually the nucleus will have enough energy in thermal motion to overcome the residual strong forces holding the nucleus together and we'll end up with just the protons. Eventually you can heat it up enough that the strong force isn't enough to hold the quarks together too! Those would be some hugely energetic photons!
The point I was making was more about the processes we can use to generate x-rays. It is terribly inefficient to try to produce them with a plasma for us, but for stars; well, it's the only way to go. Neat stuff regardless. - borg359, on 10/12/2007, -0/+0@shimavak
Heating objects to a temperature where they emit blackbody radiation peaking in the x-rays isn't very hard in astrophysical systems. The accretion disks around black holes are the classic example, where plasma that's rotating around in the disk is heated through viscosity to extremely high temperatures. Gamma-ray Bursts are another, where thermal components can be seen all the way up to gamma-ray regime, meaning the plasma is extremely hot. - inactive, on 10/12/2007, -3/+2For all you creationists, God eating and then pooping.
- antechinus, on 10/12/2007, -2/+1God wouldn't allow this to happen. Marked down for being unGodly.
- timmertc, on 10/12/2007, -7/+5Science and Religion are not incompatible. Science is just the process of understanding what God created and discovering the properties He used. It's a perpetual series of new discoveries.
- Pic0, on 10/12/2007, -5/+3Light is matter traveling at the speed of light?
am I Pic0 traveling at the speed of Pic0? - killn00bz, on 10/12/2007, -4/+1gamma rays are harmful to the body so i wonder if it is close enough to effect us.
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