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LHCb Experiment Observes New Matter-Antimatter Difference

Posted by Unknown on from the anti-matter-was-fired-years-ago dept.

An anonymous reader writes "Matter and antimatter are thought to have existed in equal amounts at the beginning of the Universe, but today the Universe appears to be composed essentially of matter. By studying subtle differences in the behavior of particles and antiparticles, experiments at the LHC are seeking to cast light on this dominance of matter over antimatter. Now the LHCb experiment has observed a preference for matter over antimatter known as CP-violation in the decay of neutral B0s particles. The results are based on the analysis of data collected by the experiment in 2011."

78 of 129 comments (clear)

  1. I'm Definitely Antimatter by Anonymous Coward · · Score: 5, Funny

    Now the LHCb experiment has observed a preference for matter over antimatter known as CP-violation

    If the pro-matter people are violating CP laws, I want nothing to do with them.

    Just Say No to matter!

    1. Re:I'm Definitely Antimatter by game+kid · · Score: 1, Funny

      You vile soulless lapdog! Those Civil Protection jackboots must be disobeyed as often as possible!

      --
      You can hold down the "B" button for continuous firing.
    2. Re:I'm Definitely Antimatter by Anonymous Coward · · Score: 2, Funny

      But by preferring antimatter to matter, you're also violating CP laws. Down with matter-ism!

    3. Re:I'm Definitely Antimatter by gomiam · · Score: 1, Offtopic

      I am completely amatteurish, and I don't know which one is better.

    4. Re:I'm Definitely Antimatter by steelfood · · Score: 1, Flamebait

      We need more restrictive CP laws so that it'll be harder for them to be violated in the future.

      --
      "If a nation expects to be ignorant and free in a state of civilization, it expects what never was and never will be."
    5. Re:I'm Definitely Antimatter by K.+S.+Kyosuke · · Score: 2

      Just Say No to matter!

      I've been saying "no" my whole life and I still don't matter.

      --
      Ezekiel 23:20
    6. Re:I'm Definitely Antimatter by cheater512 · · Score: 1

      But you don't matter.

    7. Re:I'm Definitely Antimatter by DaBigMan · · Score: 1

      Who cares about laws anyway? Just wait for the politicians - they will change them on the fly...

  2. A: Becuase it breaks the flow of a message by DNS-and-BIND · · Score: 5, Informative

    Q: Why is starting a comment in the Subject: line incredibly irritating?

    --
    Shutting down free speech with violence isn't fighting fascism. It IS fascism!
  3. equal amounts at the beginning of the Universe by Anonymous Coward · · Score: 1

    Matter and antimatter are thought to have existed in equal amounts at the beginning of the Universe

    yes, both zero at the beginning.

    1. Re:equal amounts at the beginning of the Universe by UnknownSoldier · · Score: 1, Funny

      /sarcasm. Right, the universe just spontaneous came into existence.

      From the Laws of Thermal Dynamics we know energy can not be created nor destroyed.
      Einstein showed us all Matter is Energy.
      Therefore the Universe has ALWAYS existed in one form or another.
      Q.E.D.

    2. Re:equal amounts at the beginning of the Universe by PhilHibbs · · Score: 1, Interesting

      My theory is, that matter and antimatter did exist in equal amounts. Matter travels one direction in time, antimatter travels the other direction. So the two forms of matter headed of in different temporal directions, and the original matter and antimatter will never meet. Antimatter can be created in high energy interactions though, which explains why there is some around, but that isn't the original antimatter.

    3. Re:equal amounts at the beginning of the Universe by i+kan+reed · · Score: 5, Insightful

      You say "QED" like science is a closed method of understanding like logic is. The scientific method makes acknowledgement that its results are only accurate in as far as the controls we've been able impose in our experimentation and observation hold. We have never tested the laws of thermodynamics in conjunction with a singularity, and thus anything we say about their behavior there is an extrapolation. Extrapolation isn't induction, and what you just said isn't a proof.

    4. Re:equal amounts at the beginning of the Universe by PhilHibbs · · Score: 1

      The second law of thermodynamics applies within our universe. Who knows what laws governed the creation of that universe in which that law applies? Maybe there's something outside what we naively call "the universe" from which the energy came?

    5. Re:equal amounts at the beginning of the Universe by lister+king+of+smeg · · Score: 1

      /sarcasm. Right, the universe just spontaneous came into existence.

      From the Laws of Thermal Dynamics we know energy can not be created nor destroyed.
      Einstein showed us all Matter is Energy.
      Therefore the Universe has ALWAYS existed in one form or another.
      Q.E.D.

      you are forgetting zero point energy where a negative and a positive particle spontaniously (for lack of a better word) spawn and then annihilate each other leaving the balance at zero. this does not violate thermodynamics as the balance is maintained. Is it possible that the universe is nothing more than a very large zero point even where the antimatter will eventually annihilator all the matter?

      --
      ---Saying gnome 3 is better than windows 8 not so much a compliment as it is damning with light praise.
    6. Re:equal amounts at the beginning of the Universe by Anonymous Coward · · Score: 1

      That's the problem, there isn't enough anti-matter to annihilate all of the matter. There is a lack of symmetry in the creation of matter and anti-matter.

    7. Re:equal amounts at the beginning of the Universe by Anonymous Coward · · Score: 2, Informative

      If that were the case, then reactions that produce anti-matter would be detectable before they occur.

    8. Re: equal amounts at the beginning of the Universe by Gilmoure · · Score: 1

      All physical laws breakdown before Big Bang.

      --
      I drank what? -- Socrates
    9. Re:equal amounts at the beginning of the Universe by Anonymous Coward · · Score: 1

      Why do you think they move in different directions causing them to not meet? There is nothing to support this. Matter and Anti-matter pretty much are the same, other than they cancel out on contact and revert back to energy. There seems to be a bias in the creation of anti-matter, which is strange.

    10. Re:equal amounts at the beginning of the Universe by i+kan+reed · · Score: 1

      Hmm, parts of this are accurate and really not contrary to my point, and parts are downright crazy, incorporating some sort of bizarre nationalism, a fundamental misunderstanding of the scientific method, and directionless babble about how wrong I(or was the GP?) am about something non-specific. I have a feeling that if I could parse your underlying point out from that word-salad I'd disagree, but I can't even say that for sure.

    11. Re: equal amounts at the beginning of the Universe by i+kan+reed · · Score: 1

      See, but that's a positive assertion that's actually quite unprovable. We know there are a subset that cannot operate as we define them today because contradictions would arise, but that's not the same as them. There may be underlying rules/laws to the ones we use today that would continue to make sense under those conditions.

      I'm not saying there are, but you're the one making a positive assertion.

    12. Re:equal amounts at the beginning of the Universe by Culture20 · · Score: 2

      Without the universe there's no concept of causality and no concept of time. ... The universe could still have come into existance all on its own.

      Time is the dimension upon which we measure change. Without a dt, dv doesn't happen. Without time, how does the universe change from non-existing to existing?

    13. Re:equal amounts at the beginning of the Universe by buchner.johannes · · Score: 4, Interesting

      /sarcasm. Right, the universe just spontaneous came into existence.

      From the Laws of Thermal Dynamics we know energy can not be created nor destroyed.
      Einstein showed us all Matter is Energy.
      Therefore the Universe has ALWAYS existed in one form or another.
      Q.E.D.

      Indeed, the curvature of the universe corresponds to negative energy, which can make the energy budget zero. See "A universe from nothing" by Lawrence Krauss (talk here) on why the energy budget can be zero.

      One aspect in the big bang is that you can borrow energy from quantum mechanics if you give it back within a short time (the time needs to be shorter the more energy you borrow). Combine this with extremely fast inflation and you can run away with the energy you borrowed.

      --
      NB: The message above might reflect my opinion right now, but not necessarily tomorrow or next year.
    14. Re:equal amounts at the beginning of the Universe by digitig · · Score: 5, Interesting

      Matter and antimatter are thought to have existed in equal amounts at the beginning of the Universe

      yes, both zero at the beginning.

      Creation of matter from zero matter is a violation of the second law of thermodynamics. Not that I say that you are wrong, just that it doesn't seem likely that both are right.

      The simple answer to that is that the second law of thermodynamics is a statistical law, not an absolute one. Entropy in a system can increase with time, but the overall trend is always for entropy to increase. You can see the universe as a temporary statistical blip.

      The more accurate answer is to observe that there are issues with the understanding of time itself implied by your observation. On the usual model of the big bang, time itself came into existence at the big bang. Because there was no "before" the big bang, the rate of change of entropy is undefined at the point of the big bang -- it would be the gradient at a singularity, and there's no such thing, so the second law of thermodynamics is meaningless at that point. (And of course even that is a simplification, because phrases like "came into existence" assume time's arrow, which is pretty hotly disputed).

      --
      Quidnam Latine loqui modo coepi?
    15. Re:equal amounts at the beginning of the Universe by camperdave · · Score: 2

      There is a lack of symmetry in the creation of matter and anti-matter.

      How do we know this? How do we know that a distant galaxy isn't completely made of antimatter? Does anti-hydrogen fusion in an antimatter star produce a different spectrum than normal hydrogen in a normal matter star?

      When the Big Bang happened, both matter and antimatter were created. A goodly amount of it found its opposite and annihilated back to energy. However, the universe was expanding at the time. Eventually the universe would be big enough that a particle and antiparticle could fly away from each other and never meet. There could have been regions where matter predominated, and regions where antimatter did. Maybe the empty spaces between galaxies is where the particle/antiparticle density was roughly the same, and the galaxies are where one type predominated.

      --
      When our name is on the back of your car, we're behind you all the way!
    16. Re:equal amounts at the beginning of the Universe by Roger+W+Moore · · Score: 2

      It's not just time: how does anything exist if there is no space?

    17. Re: equal amounts at the beginning of the Universe by Electricity+Likes+Me · · Score: 4, Insightful

      This is incorrect. All currently known laws become meaningless as all your variables go towards infinity. This doesn't mean there are no laws - simply that we lack the theory to describe them in such extreme conditions.

      It's the "what's infinity * infinity? Infinity!" - it doesn't really describe anything real. Of course, this situation changes dramatically if we could show that the variables didn't go to infinity, but were bounded in some fashion. Presently, we can't though.

    18. Re:equal amounts at the beginning of the Universe by maxwell+demon · · Score: 1

      One aspect in the big bang is that you can borrow energy from quantum mechanics if you give it back within a short time (the time needs to be shorter the more energy you borrow). Combine this with extremely fast inflation and you can run away with the energy you borrowed.

      So you are saying the early universe was just like our financial system? ;-)

      --
      The Tao of math: The numbers you can count are not the real numbers.
    19. Re:equal amounts at the beginning of the Universe by Spinalcold · · Score: 1

      Not only that but conservation of energy doesn't hold for the universe on a whole, only locally. At least that's the current theory, it could be proven wrong. For evidence look at the expanding universe and the cosmic microwave background. All the energetic photons created after the big bang have lost energy as they have shifted down to 3 K. Again, this could be proven wrong because we have no clue what the vacuum energy really is, any time it's calculated from quantum mechanics the energy is thousands of orders of magnitude too large. But the current theory is that energy is NOT conserved in the universe as a whole.

    20. Re:equal amounts at the beginning of the Universe by digitig · · Score: 1

      Of course, what I meant to type was that entropy can temporarily decrease, but the overall trend is always to increase.

      --
      Quidnam Latine loqui modo coepi?
    21. Re:equal amounts at the beginning of the Universe by painandgreed · · Score: 1

      There is a lack of symmetry in the creation of matter and anti-matter.

      How do we know this? How do we know that a distant galaxy isn't completely made of antimatter?

      Basically because from things like the cosmic background radiation and other evidence, we can determine what the original conditions of the universe were like. In the time of primordial nucleosynthesis, about three minutes after the big bang, things were becoming cool enough for matter and anti-matter to form. In this time, things were still pretty well mixed and it was too hot for a nucleus to capture electrons or positrons, so matter and anti-matter were recombining as they were drawn to each other and annihilated. By time the universe was cool enough for atoms to form, matter dominated everything. If it didn't, then things would end up looking different as it would have taken a lot longer for stars and galaxies to form if they were constantly destroying each other till somewhat stable regions of matter and anti-matter formed. I imagine that the cosmic background radiation would end up looking a lot less even as there would be more coming from the boundry areas between those regions. Add in that we have looked and do not see any evidence of any large scale matter anti-matter events which we would expect if half (or any significant fraction) of the galaxies (let alone stars) out there we anti-matter.

      So, matter and anti-matter must have been separated somehow in the early universe. The most likely answer would be that matter outnumbered anti-matter which would cause it to become dominant very quickly as in the early universe when everything was very well mixed and being created and destroyed regularly, each so called generation of matter/anti-matter generation would leave behind more and more matter which would annihilate the anti-matter even quicker till all available energy ended up as matter. Coming up with something like all matter went left while anti-matter went right causing no real boundry region would just mess up the idea of an isotropic universe. The only other even fanciful solution I could think of is to follow long with the anti-matter is just matter travelling backwards in time, and thus all the originally created anti-matter never annihilated with matter because it quickly went backwards in time away from the matter traveling forwards in time with the same momentum. Of course, then you have really difficult issues with the time before that because time probably didn't exist before such a situation as it is the opposite movements at their creation that created time. once again, if such were the case, I imagine we could figure out that the early universe would have looked much different than what we are seeing evidence of.

    22. Re:equal amounts at the beginning of the Universe by UnknownSoldier · · Score: 1

      > how does anything exist if there is no space?

      So the number 2 does't exist? Infinity doesn't exist?

      You seem to be greatly confused about meta-physics. Physical reality is only a tiny subset of much larger reality that scientists are generally clueless about.

    23. Re:equal amounts at the beginning of the Universe by Roger+W+Moore · · Score: 1

      So the number 2 does't exist? Infinity doesn't exist?...Physical reality is only a tiny subset of much larger reality that scientists are generally clueless about.

      Perhaps I am being overly scientific here but that "larger reality" is in your head, which is a complex physical system operating in our physical reality and hence any thought you may have is part of our physical reality - it's the quantum state of your brain. Hence the number two represents an abstract concept designed to be relevant to our universe. Frankly if you have no space and no time then I'm not convinced that the number 2 does exist or have any meaning - 2 what?

      Clearly the universe came from somewhere but that is the only physical evidence that reality is more than our universe. Calling your own thoughts and concepts a "larger reality" is false because you can easily conceive of things that are not real. Perhaps whatever came before the Big Bang allowed for the existence of mathematical concepts as we understand them but, without evidence to that effect it is nothing more than supposition which does not make it real.

  4. Re:A: Answering a question by Dupple · · Score: 1

    before it's asked is even worse

    --
    Watch those corners
  5. CP by MagicM · · Score: 4, Funny

    "CP-violation"

    Right. Like I'm going to click on that link.

  6. I know /. editors love CERN by Lawrence_Bird · · Score: 3, Informative

    but the headline is a bit grandiose - there is nothing new about CP violation. CP violation has been known for a very long time and there are at least three other examples of it prior to LHCb report. Also, as CERN notes, others were not able to accumulate sufficient statistics to make the observational claim. Perhaps "CERN's LHCb confirms CP violation in another particle" my be both a more accurate way of describing it and also less "omg, ponies!"

    1. Re:I know /. editors love CERN by hajus · · Score: 5, Informative

      For the electroweeak force yes, but not in the QCD Lagrangian. B+ meson CP violation is the new part.

    2. Re:I know /. editors love CERN by mu22le · · Score: 2

      I think the headline is correct, LHCb has observed CP violation in an experimental domain where it had not been observed before. The headline does not claim that LHCb has discovered CP violation.

    3. Re:I know /. editors love CERN by Anonymous Coward · · Score: 1

      this is still the same CKM quark mixing. finding CP violation in the QCD lagrangian would be *really* big news.

    4. Re:I know /. editors love CERN by lgw · · Score: 1

      But this was predicted years ago, right? (IIRC there are two commonly predicted CP violations) This is "just" experimental confirmation?

      --
      Socialism: a lie told by totalitarians and believed by fools.
    5. Re:I know /. editors love CERN by SleazyRidr · · Score: 2

      Sometimes I think people are just trolling /. by posting random letters that look like physics, then I spend some time on Wikipedia and realise how little I know.

      --
      Is 1563649 a prime number?
    6. Re:I know /. editors love CERN by BitterOak · · Score: 2

      Actually the GP (AC) is absolutely right, and GGP (hajus) has it wrong. CP violation in a strong decay would be really big news. Strong decays aren't even believed to exhibit P or C violation separately. What this experiment observed was CP violation in decays of the B^0_s (B superscript 0 subscript s) meson, a weakly decaying particle. (This meson consists of a bottom quark together with an anti-strange quark). This is the fourth particle for which CP violation has been observed, the first seen by Fitch and Cronin in decays of the neutral K meson. This is exciting news, but it has nothing at all to do with QCD.

      --
      If I can be modded down for being a troll, can I be modded up for being an orc, or a balrog?
  7. Re:What if light travels REAL SLOW by wonkey_monkey · · Score: 5, Insightful

    What if monkeys can actually talk but refuse to do so because they don't want us to know?

    What if quarks are actually microscopic doughnuts, and we can fly through them into an alternate universe where Snooki is president?

    What if... ah, screw it, if you can't see where I'm going with this by now there's no hope for you.

    --
    systemd is Roko's Basilisk.
  8. Re:What if light travels REAL SLOW by NatasRevol · · Score: 1

    What if space is matter and there's no such thing as a vacuum?/quote

    NASA is going to be PISSED!!!

    --
    There are two types of people in the world: Those who crave closure
  9. Re:A: Answering a question by Zero__Kelvin · · Score: 1

    Nobody asked what was worse!

    --
    Guns don't kill people; Physics kills people! - John Lithgow as Dick Solomon on Third Rock From The Sun
  10. Re:I'm still not convinced... by ThePeices · · Score: 2

    ...that we are definitely made of matter. If we were made of anti-matter, wouldn't matter actually look like anti-matter to us, only because it isn't what we're made of?

    Not really. We have defined an electron (matter) as the electron-particle that has a negative electric charge. A positron (anti-electron, antimatter) is an electron with a positive charge. Same goes for protons etc, and we know for certain that we and all the matter around us are composed of the 'matter' version.

    Also, if matter and anti-matter existed in equal amounts at the beginning, wouldn't the remaining particles, regardless of what they are (after all the self-annihilation and whatnot) be considered matter by default?

    No, because if they were equal in quantity, the left over particles would be a 50-50 mix of matter and antimatter, but this is not the case in reality.

  11. Re:What if light travels REAL SLOW by Ioldanach · · Score: 1

    What if space is matter and there's no such thing as a vacuum?

    That's it! All we have to do is dephlogisticate a large quantity of rocket fuel and we'll reach the aether!

  12. Re:What if light travels REAL SLOW by PhilHibbs · · Score: 1

    Imagine if a photon travels not much faster than an electron (a few cms a second)...

    Electrons can and often do travel much faster than that, but they go round and round in tiny circles and only drift through a conductor at an aggregate speed of a few cm per second. An electron's actual speed is, as with all physical things, based on its energy. You might as well imagine how fast rocks travel.

  13. Car Analogy by raftpeople · · Score: 1

    It's normal to find coins under the seat, this time they found coins inside the seat.

  14. How do we know by wisnoskij · · Score: 1

    What type of matter most of the universe is made of? Past this particular gravity well of our sun, how do we tell that the rest of the planets and stars are not anti-matter planets and anti-matter stars?

    --
    Troll is not a replacement for I disagree.
    1. Re:How do we know by Anonymous Coward · · Score: 2, Insightful

      Well, let me start by saying I don't know anything about this field. However, it seems to me that the interstellar medium is that kind of combination of really close to a vacuum and really big that still allows for quite a lot of particles out there hitting the edge of our solar system (I believe we're close to (or already are) getting actual measurements from probes we've sent out that have already left or will soon leave the solar system). Where these collisions occur, we'd expect matter-antimatter pairs to self-annihilate, and we could observe that. Since we don't, then the interstellar medium is made of matter. Likewise, if there were some antimatter stars out there, there would be a boundary between antimatter and matter in the interstellar medium and we could see the self-annihilations through observation. Maybe there are whole antimatter galaxies out there, but then again, we have discovered instances of galaxies that are colliding or have collided. Similar to stars passing through the interstellar medium, it seems we would be able to observe the matter-antimatter annihilation in at least some if they were in equal proportion.

    2. Re:How do we know by Brucelet · · Score: 1

      If there were large pockets of matter and anti-matter in different places, then there would be boundaries between them where annihilations are frequent. We observe no such boundaries.

    3. Re:How do we know by thrich81 · · Score: 1

      Read the AC comment before mine, it says about about what I was going to say. Certainly within galaxies and galaxy groups, there are enough interactions that we would see the results of the matter-antimatter annihilation if there were significant amounts of both, especially gamma rays at the energy of electron-positron annihilations. And many cosmic ray particles come from a long ways out, maybe even intergalactic, I think -- if there was a lot of antimatter out there we would see more antimatter in the incoming cosmic rays. Actually the AMS experiment on the ISS is directly measuring the presence of antimatter (mostly positrons) in the cosmic rays which make it to the vicinity of the earth. They aren't seeing much -- certainly not enough to support the presence of antimatter stars, gas, etc in our galaxy.

    4. Re:How do we know by wisnoskij · · Score: 1

      But matter grouts together with indistinct borders that are not often crossed.

      We are in the The Milky Way galaxy, it is probably fair to say that it is made of a vast majority of matter.

      But how do well know that the Andromeda Galaxy is not made of a vast majority of antimatter.

      --
      Troll is not a replacement for I disagree.
    5. Re:How do we know by Brucelet · · Score: 1

      If antimatter galaxies were common, then we'd see collisions between matter and anti-matter galaxies which would be radically different and more energetic than the collisions we do see.

  15. Re:What if light travels REAL SLOW by Anonymous Coward · · Score: 5, Funny

    What if space is matter and there's no such thing as a vacuum?/quote

    NASA is going to be PISSED!!!

    Slashdotter discovers simple $5 trick that makes NASA scientists FURIOUS! Click your age to discover this trick for yourself!
    [ <18 ] [ 18 - 24 ] [ 25 - 40 ] [ 41 - 55 ] [ 56 - 70 ] [ 71+ ]

  16. Re:I'm still not convinced... by VortexCortex · · Score: 1

    We have defined electron as matter only because it is part of what we're made of. If however, atoms were composed of positrons instead of electrons, wouldn't electrons be considered anti-matter?

    Perhaps, but that's the thing. Super symmetry doesn't exist, so things would work differently in the anti-matter dominated universe.

  17. Re:I'm still not convinced... by Brucelet · · Score: 1

    Sure, but that's not relevant. We have chosen to label the stuff that dominates our universe as matter because it's what we saw first. Ultimately though it's just a name. We could call them this-matter and that-matter and the physics wouldn't change.

  18. Re:I don't get it by wonkey_monkey · · Score: 1

    The universe would still exist even if it was empty; there'd just be no-one around to observe it (unless you want to get ridiculously philosophical about that). So no, it wasn't required to be that way, it's just lucky for us that it was.

    There may well be other universes (sidebar: there are several different classes of things you can call "universes") where there is no matter or antimatter, but there are probably no conscious beings in there.

    --
    systemd is Roko's Basilisk.
  19. CP violation by VAXcat · · Score: 1

    Matter...Anti-Matter...I'm the guy with the gun.

    --
    There is no God, and Dirac is his prophet.
  20. Meanwhile.... by moeinvt · · Score: 2

    Meanwhile, in a parallel universe: "...experiments at the LHC are seeking to cast light on this dominance of antimatter over matter."

    1. Re:Meanwhile.... by jfengel · · Score: 2

      Except they call it the CHL.

    2. Re:Meanwhile.... by Anonymous Coward · · Score: 1

      No, the headline would be exactly the same. THAT's curious.

    3. Re:Meanwhile.... by knorthern+knight · · Score: 1

      > Meanwhile, in a parallel universe: "...experiments at the LHC are
      > seeking to cast light on this dominance of antimatter over matter."

      Actually, they would consider their form of matter to be "matter" and "the other kind" would be "anti-matter".

      --

      I'm not repeating myself
      I'm an X window user; I'm an ex-Windows user
  21. Christopher Walken approves of the parent post. by sconeu · · Score: 1

    We could call them this-matter and that-matter and the physics wouldn't change.

    You can go with this or you can go with that

    --
    General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
  22. Re:What if light travels REAL SLOW by Artifakt · · Score: 2

    James Dyson is going to be even more pissed. Freeman Dyson probably will be too. Why is the AC trying to piss off all sorts of Dysons?

    --
    Who is John Cabal?
  23. Re:What if light travels REAL SLOW by MiniMike · · Score: 4, Funny

    James Dyson is going to be even more pissed. Freeman Dyson probably will be too. Why is the AC trying to piss off all sorts of Dysons?

    He's probably hoping all the Dysons come to see him at the same time and angrily surround him.

    He will then claim that he has the only Dyson sphere made out of real Dysons.

  24. Good question! by Roger+W+Moore · · Score: 5, Informative

    How do we know this?

    We know this by looking for gamma rays produced by matter/anti-matter annihilations. The solar wind does not annihilate with out atmosphere so we know the sun is made of matter. This same wind does not annihilate with the interstellar medium in the galaxy so that is made of matter. No other star has visible annihilation lines with this medium either so we can be sure the entire galaxy is made of matter. Further out out galaxy does not create annihilations with the medium in the local super cluster of galaxiesand neither does any other galaxy so we know that the local super cluster is all made of matter.

    To go further afield is harder since at this point the distances rule out detecting gamma rays from the incredibly sparse intergalactic medium (at least this was true several years ago - perhaps astronomers can do better now?). So instead what you can do is look at galactic collisions. No colliding pair of galaxies emits gamma radiation consistent with annihilation events so either the universe is really perverse and somehow no pair of colliding galaxies is ever a matter/antimatter pair OR there are no anti-matter galaxies out there to collide with. So while it is impossible to rule out that there might be one or two anti-matter galaxies hiding in some distant corner of the universe there are clearly far, far more matter galaxies than anti-matter ones.

    1. Re:Good question! by camperdave · · Score: 2

      Well, alrighty then. Thanks for the well articulated, easy to understand answer.

      --
      When our name is on the back of your car, we're behind you all the way!
  25. First Law of Thermodynamics by Roger+W+Moore · · Score: 3, Informative

    Actually there is. Of course it is only interested in thermal energy but nevertheless it is there. One of the most beautiful bits of mathematics, Nöther's Theorem, shows that for any symmetry there must be a conservation law (or vice versa). For energy the cause of the conservation law is that the laws of physics are all symmetric under translation in time i.e. the laws of physics today are the same as they were yesterday. So while the reason for energy conservation has nothing to do with thermodynamics it is still stated as its first law.

    1. Re:First Law of Thermodynamics by maxwell+demon · · Score: 1

      The big bang as we currently assume it is clearly not symmetric under translation in time. There's a clear distinction between "before big bang" (doesn't exist) and "after big bang" (does exist). Therefore Nöther's Theorem doesn't predict energy conservation at the big bang.

      --
      The Tao of math: The numbers you can count are not the real numbers.
    2. Re:First Law of Thermodynamics by Roger+W+Moore · · Score: 1

      The big bang as we currently assume it is clearly not symmetric under translation in time.

      Careful - I have heard some speculation from cosmologists that time may have existed prior to the Big Bang in which case energy may well have been conserved. However if the Big Bang created time and without time there is no concept of energy then obviously in these circumstances energy cannot be conserved. However my response was to the OP's claim that thermodynamics had no law about energy conservation which is clearly untrue.

    3. Re:First Law of Thermodynamics by maxwell+demon · · Score: 1

      Careful

      How was "as we currently assume it" not careful enough?

      --
      The Tao of math: The numbers you can count are not the real numbers.
    4. Re:First Law of Thermodynamics by Roger+W+Moore · · Score: 1

      How was "as we currently assume it" not careful enough?

      We do not assume that the Big Bang was asymmetric under translation in time: it might have been or it might not have been. There is no data to justify an assumption one way or the other hence "careful".

  26. Re:A: Answering a question by berashith · · Score: 1

    who asked what was worse?

  27. Re:I don't get it by femtobyte · · Score: 2

    Yes, from an "anthropic principle" perspective you've pretty much got to somehow end up with a universe with a matter/antimatter imbalance in order to have folks to see it. The interesting physics question, however, would be to understand how said necessary matter imbalance was produced. For example, perhaps matter and antimatter behave exactly the same, and we're just in a local "bubble" where early-universe statistical fluctuations coughed up a bit more matter. On the other hand, maybe we can find differences in the properties of matter and antimatter (which experiments like this indicate) that might allow one to be preferentially produced over the other.

  28. Re:A: Answering a question by Zero__Kelvin · · Score: 2

    Who's on first, and didn't ask what was worse. I Don't Know didn't ask what was worse either.

    --
    Guns don't kill people; Physics kills people! - John Lithgow as Dick Solomon on Third Rock From The Sun
  29. Re:A: Answering a question by DNS-and-BIND · · Score: 1

    So, in other words...it...breaks the flow of a message?

    You see what I did there?

    --
    Shutting down free speech with violence isn't fighting fascism. It IS fascism!