LHC :: Pb-Pb Collisions :: mBH

Discussion in 'Physics & Math' started by hahnaz, Mar 27, 2015.

  1. rpenner Fully Wired Valued Senior Member

    Messages:
    4,833
    Anyone can invent a story, even a scientific-themed disaster story. But such stories are not the equivalent of informed speculation on the behavior of the universe. Scary stories are distinct in many ways from credible physical hypotheses. Maybe you and your family member lack the ability to distinguish them, but professional scientists

    First of all, in 2008 a member of this forum attempted to sue to stop the Large Hadron Collider. He was wrong on every point, legal and scientific, despite even earlier attempts to stop RHIC and possibly Bevatron.
    Likewise, Otto E. Rössler also made claims and sued, but didn't publish scientific papers with calculations that would convince anyone. While he once had a fine reputation in unrelated scientific fields, he appears to have "gone emeritus" and was last seen self-publishing in a vanity press organ.
    They got plenty of scientific, especially in 2008 when a suicide was attributed to credulous adoption of the scare story, and lay press coverage, but never made their case. This forum's member was even mocked by John Oliver for using a completely incoherent misstatement of basic probability theory as a principle basis. When you get schooled on your mathematics by a tongue-in-cheek interviewer, you aren't a credible source of new physics information.
    http://www.sciforums.com/threads/lhc-safety-and-the-law.85716/
    http://en.wikipedia.org/wiki/Safety_of_high-energy_particle_collision_experiments

    Second, the spectrum of Cosmic Rays includes some very high energy particles moving in every direction. (What matters in collisions is per particle energy.) Naturally, some of them will collide with each other and this demonstrates that there is no existential threat to the universe from such collisions or the universe would be filled with a gas of tiny black holes or other such existential threats.
    http://en.wikipedia.org/wiki/Cosmic_ray

    Thirdly, by the standard laws of gravity, any such TeV-scale black hole would have a radius many times smaller than a proton, so they could not be more efficiently formed by Pb-Pb collisions than by proton-proton collisions. That's because protons aren't solid objects but at these collision energies are effectively a nearly free gas of quarks and gluons. Neither would they have more gravity than a regular particle with the same mass, and gravity is very weak compared to the nuclear and electrical forces which dominate. Likewise, the conservation of angular momentum means they don't suck matter as depicted in Hollywood. The black hole at the center of the galaxy is orbited by stars than move very fast and come very close but don't just get pulled in.

    Fourthly, the possibility of a unstable black holes that pose just a threat to humanity or Earth is ruled out by the long lifetime of very dense stars which should also be quickly devoured if the laws of physics allowed dangerous black holes to be formed.

    http://arxiv.org/abs/0806.3381
    http://arxiv.org/abs/0806.3414
    http://arxiv.org/abs/0807.3349

    Finally, the LHC that will start up a few weeks from now is only about twice as strong (measured in per-particle energy) as the one that ran before, not the millions of times more of individual Cosmic Rays.
     
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. Q-reeus Banned Valued Senior Member

    Messages:
    4,695
    hahnaz; in addition to other comments, the following may help as it relates specifically to false vacuum decay scenario:

    Conversion factor between particle mean temperature in Kelvin and energy in eV is ~ K = 10^-4 eV :https://en.wikipedia.org/wiki/Electronvolt#Temperature
    Now check out the temperatures characteristic of various epochs in standard BB/inflation scenario: http://www.astro.ucla.edu/~wright/BBhistory.html
    Notice that start of hot BB (after inflation phase has ended and current false vacuum applied) is ~ 10^27 K to 10^28 K, translating to 10^11 TeV to 10^12 TeV per particle.
    Restricting numbers to just that relating to our current Hubble volume, ~ 10^82 particles with such mean energies were colliding continually at extremely high collision rates. Not until ~ 10^-4 seconds was the mean temperature down to ~ 10 TeV. And remember there is a high energy tail to the temperature distribution involving far higher energies than mean value.

    Unless I am missing something basic and rather subtle, above suggests the standard hot BB scenario has automatically ruled out any possibility of catastrophic decay of false vacuum as per your nightmare fears. And if it did happen, be comforted with the thought it would all be over before any sensation of pain could reach your annihilated brain.

    Please Register or Log in to view the hidden image!

     
    hahnaz likes this.
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. brucep Valued Senior Member

    Messages:
    4,098
    Very informative post. Your scholarship is showing. Thanks.
     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. hahnaz Registered Member

    Messages:
    42
    "Because the species of cosmic rays (CR) with similar energies as LHC`s planned lead (Pb-Pb) collisions with 1`066 TeV center of mass (c.o.m.) energy is not known, it is not possible to calculate the exact c.o.m. energies of these CR."

    If Pb - Pb collisions do not occur, and that energy is never created through Pb-Pb Collisions how can we be sure it is safe is my argument. It was said here that Pb collisions do not reach 1,066TeV in nature, is this not dangerous as according to the Vacuum Bubble theory?

    Could Pb-Pb frequency/luminousity be non comparitice to CR and invalidate to CR arguements in the LSAG report? over 1k TeV!!!!! <- Tottoli did the mathematics on it showing how high it was. Seems ridiculusly high to me especially if a big deal was made over 14TeV p-p collisions.
     
  8. hahnaz Registered Member

    Messages:
    42
    "Because the species of cosmic rays (CR) with similar energies as LHC`s planned lead (Pb-Pb) collisions with 1`066 TeV center of mass (c.o.m.) energy is not known, it is not possible to calculate the exact c.o.m. energies of these CR."

    If Pb - Pb colissions do not occur, and that energy is never created how can we be sure it is safe is my argument. People here even said it, Pb collisions of that energy do not exist in nature.

    3.5 TeV per beam (per proton) was 2010.
    The 1148 TeV is the entire collision energy of two Pb ions, more exactly each Pb ion with 574 TeV resp. each nucleon of Pb ion with 2.8 TeV, at LHC design energy, please see abstract here:
    http://iopscience.iop.org/1748-0221/3/08/S08001/
    The statement of CERN`s LSAG safety assesment group that: "Nature has already completed about 10^31 LHC experimental programmes since the beginning of the Universe." and all the similar statements and cosmic ray comparisons are only relevant for the LHC`s programme of proton-proton collisions of 14 TeV per collision but they don`t compare cosmic rays with the LHC`s Pb-Pb collisions, one can only guess why...!


    1148 TeV is SIGNIFICANTLY higher energy than the safety report for RHIC said it was safe to do so, is this cause c.o.m. measurement is different? I'm super confused on that part

    rpenner - were there not a few scientists do agree with the possibilities of danger:

    http://iopscience.iop.org/1742-6596/230/1/012044/pdf/1742-6596_230_1_012044.pdf

    New solutions for the color-flavor locked strangelets
    Prof. Guang Xiong Peng, Xin Jian Wen and Yuede Chen (2005)
    A paper reporting that the charge of color-flavor locked strangelets can be positive, negative, or
    nearly neutral.
    http://arxiv.org/abs/hep-ph/0512112
    see also:
    http://arxiv.org/abs/hep-ph/0612253

    "Though there may be more energetic cosmic ray collisions than 1148TeV but their species is not known. According to physicists, heavy ions are more suitable to induce large vacuum bubbles which could expand and lead to a catastrophic vacuum transition of the universe. It is possible that Pb-Pb collisions with energies as at the LHC (=1148TeV) do not occur in the universe."


    Is this not a large concern? mBH does not seem to be the worry anymore, Vacuum Instability or papers like the previous 2.

    Once again I am not attempting to gather fear. I am truly trying to suppress my own.
     
  9. Daecon Kiwi fruit Valued Senior Member

    Messages:
    3,133
    You're not displaying fear, you're displaying paranoia.

    That means the scaremongering anti-science nutjobs are winning. Don't let them win.
     
  10. rpenner Fully Wired Valued Senior Member

    Messages:
    4,833
    First of all, neither Niccolò Tottoli nor Otto Rössler is any type of Theoretical Physicist. They are merchants of manufactured doubts. These doubts only fall apart with education so that one may distinguish good teachers from bad. Otto Rössler's skill in writing science has gotten so bad, even in his pseudo-scientific writings aping the form of a scientific article, he cites probabilities and timelines without any model or calculation. Even crazy journals he used to manage reject his attempts to be relevant to science (and math). In short, he is just making up stories when he should know better. Niccolò Tottoli is worse. He's using social media to spread a campaign of fear, uncertainty and doubt with a salting of facts.

    No one knows where you found that Niccolò Tottoli quote, because most of his output is in blog or Facebook comments, never scientific papers. You would do everyone a great favor by pointing to the actual source. Niccolò Tottoli is simply not relevant, because he is not intellectually honest.

    ⛔️ STOP! Pb-Pb collisions do occur naturally.

    Cosmic rays are mostly protons, but include nuclei including iron, gold and lead. Based on data and the long history of the visible universe, Pb-Pb collisions with center-of-mass energies well above that of the LHC should have happened a billion billion times in our history.

    http://indico.cern.ch/event/91353/contribution/45/material/slides/0.pdf
    http://arxiv.org/abs/hep-ph/9910333

    Because, all physics is local. The quarks and gluons (parton) of protons and neutrons have a radius over ten thousand times smaller than protons. And the higher the per parton energy, the more they act like an ideal gas. So all the physics that happens in the LHC is going to be about individual partons colliding into each other.

    The reason they do Pb-Pb collisions is not because of the higher energies, but because of the opportunity to study the thermodynamics of QCD and baryogenesis.

    Black holes aren't more likely to form in Pb-Pb collisions because any such black hole can only have the mass contributed by the energy of two partons, so are more likely to happen in P-P collisions where the parton energies are higher and in cosmic ray collisions where the parton energies can be are much higher.

    http://en.wikipedia.org/wiki/Asymptotic_freedom

    As I said before, even assuming black holes can form at such low masses, that doesn't make them dangerous. Not every shark is a man-eater. To fear hypothetical LHC black holes is to demonstrate one is ignorant of the phenomena of the universe.
    Because, all physics is local, the Pb-Pb collisions are not more dangerous with respect to vacuum instability than P-P collisions at the LHC which are not more dangerous than the P-P collisions which happen in Nature.

    That's not a question. Tottoli's mathematics are not in evidence on this thread and therefore no one knows if he is doing physics or even just doing irrelevant math. He could be lying for attention.

    Even if Tottoli did physics right, what standard do you use to say the difference is “ridiculously” high? The Universe is ridiculously bigger and older than the LHC, so you have to understand both the LHC and the universe before you can compare LHC and Natural results fairly.

    That is exactly what the science of physics is about.
     
    Last edited: Mar 27, 2015
    hahnaz and Dr_Toad like this.
  11. Dr_Toad It's green! Valued Senior Member

    Messages:
    2,527
    Truly. Hahnaz, you will die of old age long before any likelihood of being eaten by a runaway Sci-Fi movie can come to fruition.

    Though come to think of it, it would be less painful in the main, and one hell of a lot more exciting! For a moment, anyway.

    Please Register or Log in to view the hidden image!

     
  12. hahnaz Registered Member

    Messages:
    42
    Yes, I found most of his stuff on a LHC - Critic Facebook post/Lifeboat.com
    Not happy about finding it, just unable to decipher myself the legitimacy of his claims.


    I said it was ridiculously high because I thought 1,000 TeV is the upper limit of Pb - Pb in nature (Apparently incorrect?) - I'm not concerned about mBH creation through Heavy Ion Collision, what concerns me is the argument of Vacuum Bubble Decay.

    http://phys.org/news197217643.html
    ^ Article that suggests no Heavy Ions in Cosmic Rays


    rpenner This is exactly what I was looking for:
    The highest observed heavy ion collision in nature meassured up to 2.6 Tev, which I think that the RHIC safety assesment group claims to be the upper limit. But the upcoming heavy ion collision that is scheduled will collide particles in 7 TeV Resulting in over 1,000 TeV in energy (above the observed upper limit). Isn't this at least a little risky? I don't think that vacuum bubbles are all that easy to create, but could there be any kind of danger with these high energy heavy ion collisions?
     
  13. danshawen Valued Senior Member

    Messages:
    3,951
    rpenner is our resident expert on this question, and has answered well.

    Sylwester Kornowski also hosted part of a thread on cosmic rays which I thought was interesting, particularly these:

    http://en.wikipedia.org/wiki/Oh-My-God_particle

    Cosmic rays evidently contain intermittent bursts of these. Pray that no part of you is ever in the path of an 'Oh My God' particle. Even the recent upgrades to the energies attainable with the LHC pale by comparison.
     
  14. hahnaz Registered Member

    Messages:
    42
    I know he is. He is the reason I joined this forum. My question however is still slightly unanswered and it is the previous one. The newest addition to the thread and I am curious as to how he answers.
     
  15. arfa brane call me arf Valued Senior Member

    Messages:
    7,832
    Here is what sticks in my eye, bro.

    Your scary story appears to be based on some facts, which are: we have not observed any cosmic rays with the energy about to be "unleashed" at the LHC, and we have never collided Pb atoms together at these energies.

    First, because we here on a very small planet haven't yet observed certain things says nothing (or very little) about what goes on "out there".This is obvious: we haven't been observing high energy (or any scale) events for very long, and the planet isn't very big, why should anyone expect that we have anywhere near a good cross-section of cosmic events (I mean, seriously)?

    Next, the other part of the scary story seems to be about the stability of the current state of the vacuum, which is where my knowledge of quantum mechanics can't really take me. But I do understand that all kinds of high energy events occur constantly, and that the interior of our sun must be (according to theory) a place where events have a lot more energy than the LHC can ever hope to produce. And the vacuum hasn't turned into a bubble or anything else.

    So I would have to place the scary story firmly in the "speculative, possibly uninformed" basket, and just get on with my life.
     
    Last edited: Mar 28, 2015
  16. Q-reeus Banned Valued Senior Member

    Messages:
    4,695
    Similar statements were made in posts #5 and #20, but are not correct. Solar core temp ~ 1.4*10^7 K ~ 1.4*10^-9 TeV. Compare to LHC Pb-Pb estimated ~ 10^4 TeV and it's obvious how far out you are. Highest obtainable stellar temperatures are in a newly formed neutron star ~ 10^11 to 10^12 K ~ 10^-4 TeV tops! There is as mentioned in #22 a high energy tail to MB distribution but at those paltry mean energy levels > 10^4 TeV energies in such tails will be extremely rare.

    I have already given the overwhelmingly greatest source of ultra-relativistic events - the hot BB as per #22 (Underestimated initial particle numbers there which should have been ~ 10^90 or even higher, but that's neither here nor there given the huge general numbers and energies). To be fair it should be said there is a wide range of views about the very early conditions and events themselves, as pointed out by particle physicist Matt Strassler:
    http://profmattstrassler.com/2014/03/21/did-the-universe-begin-with-a-singularity/
    http://profmattstrassler.com/articl...ronomy-and-cosmology/history-of-the-universe/
    http://profmattstrassler.com/articl...smology/history-of-the-universe/hot-big-bang/
    (which pours a bucket of cold water over one inveterate SF poster in particular who keeps repeating the line that 'we' know the physics after first 10^-43 seconds. NOT!)
    Nevertheless, even given the most conservative initial temperature at reheating phase, IF any 'false' vacuum existed at end of inflation, such should have immediately been kicked into 'true' vacuum - IF there is any credence to the speculation high energy com collisions > ~ 10^4 TeV could kick start a bubble of 'true' vacuum. In other words, we should well and truly be in the true vacuum from that point on.
     
  17. rpenner Fully Wired Valued Senior Member

    Messages:
    4,833
    It's incorrect because 1000 TeV = 1 PeV = 0.0001 EeV and the heavy nuclei contributions to Cosmic rays don't really start to drop off until about 0.3 EeV or 300,000 TeV.
    It's incorrect, because these are kinetic energies relative to Earth and you really always want to work consistently in the center of mass energy.
    It's also incorrect because only parton-parton energies matter, not total nuclear kinetic energy. So the 10-100 EeV protons of the top end of the spectrum really do set the bar for potentially dangerous fundamental physics. A 100 EeV proton only has about 16 joules of kinetic energy, a fifth of the energy stored in a capacitor of a cheap flash camera. It's not the total energy that's important, it's that substantial parts of the energy is being delivered to the parton-parton collisions. So lead nuclei, which have many more partons than isolated protons aren't as efficient at probing new regimes of fundamental physics as are Pb-Pb collisions.

    Then ignore the Pb-Pb collisions for the reasons above. If the vacuum was the least bit unstable to LHC energies, proton-protons collisions would have erased the universe already somewhere in the past 13.7 billion-year history of the visible universe with the resulting wave of new vacuum regime moving at the speed of light.

    That's a pop-physics summary that doesn't even bother linking to the original research. The actual research says that there are many fewer Heavy Ions in Cosmic Rays above 1.6 EeV = 1,600,000 TeV, which probably points to those cosmic rays being much older (when there weren't many heavy ions) and from further away (outside the galaxy).

    Here is the actual scientific study. http://arxiv.org/abs/0910.4184 which appeared in Physical Review Letters
     
  18. OnlyMe Valued Senior Member

    Messages:
    3,914
    What part of Post #5 (quoted below) was not correct? Are you saying that the pb-pb collisions at the LHC release more energy than a fusion or fission event, in a bomb?

    Yes, my wording was intentionally non-technical and analogy. However, the point I was making is not dissimilar to your own statement(s).., events that involve energy levels in excess of those occurring in the LHC, do happen in nature.

    From rpenner's last post: A 100 EeV proton only has about 16 joules of kinetic energy, a fifth of the energy stored in a capacitor of a cheap flash camera.

    From Wiki - http://en.m.wikipedia.org/wiki/TNT_equivalent: The "ton of TNT" is a unit of energy equal to 4.184 gigajoules...

    Yes, if two protons hit dead on in a center of mass collision, such that we were observing parton-parton (that is quark-quark) collision/interactions there would be more energy released than just 2x16 joules, but no where near the potential energies expected to occur in nature.

    One would have to assume that Pb-Pb ion collisions in the LHC were ideally perfect, to even consider the possibility that energy levels might approach those associated with an un contained fission/fusion event. What actually takes place is far from ideal. There is a lot of particle debris.., meaning the ions come apart and only a fraction of their total mass results in particle-particle and parton-parton collisions.
    I suspect that some of the numbers hahnaz's sources are coming up with are assuming ideal interactions. Though indirectly, rpenner's last post, I think dealt with that pretty well​

    What occurs at the centers of stars is not un contained. There is a constant battle between gravity and the energy released through fusion of predominantly hydrogen-hydrogen... But further I believe you are making an error yourself when you speak of the energy associated with the kinds of fundamental interactions occurring either in the LHC or within the belly of a star, as confined to the associated temperatures.

    But this is straying from the initial issues. Hahnaz has over the corse of several posts now clarified his concern as related to how the particle interactions at the LHC might destabilize the vacuum (or false vacuum) and bring the whole of what we know of as reality to an end... That is total BS. Which was my initial response to his OP. The false vacuum is just another way to describe the energetic ground state, or lowest observable energy density of empty space! and we have no realistic reason to believe that there is any way that anything that could occur natually or other wise could punch a hole in our universe and allow that ground state energy level to drain out!.., leaving us with a true vacuum — a zero energy ground state — and the end of all we know. This seems to me a mixture of science fiction, several unrelated theoretical models and a total misunderstanding of the involved physics... IOW a series of quacks talking about things they do not understand in the first place, either unintentionally or perhaps even intentionally inciting fear, based on fictitious doomsday scenarios.
     
  19. Q-reeus Banned Valued Senior Member

    Messages:
    4,695
    Your statement from #5:
    The only sensible interpretation I could make of that was "peak per-particle energies (hence also collision energies) in a nuclear explosion far exceed the pending LHC Pb-Pb levels." And that is just wrong - by many orders of magnitude. If though you meant to compare the entire energy output of a nuclear bomb to that of say a LHC run involving many Pb ions at once, then sure I can agree. That though seems a very strange comparison to make as the relevant metric is energy in single com collisions.

    I agree with your remarks about the overwhelming likelihood that Pb-Pb collisions will be glancing thus 'wasteful'. However if hahnaz's fears were correct, it might only take one dead-on collision to do us all in in an instant.
    Huh? I think you skipped something. Verbatim from my #33:
    Which is true if you care to work through the math - MB distribution - even for upper temperature limit of new NS. [afaik Fermi-Dirac stats don't apply to initial ultra-hot situation] I will make one minor correction here - where I wrote ~ 10^4 TeV for pending LHC Pb-Pb collisions, it should have been ~ 10^3 TeV.

    As far as stability of false vacuum is concerned, I have little to add to what was already said. Either such has an extraordinarily high energy barrier, resistant to gazillions of reheating-era particle-particle collisions with initial mean energies quite possibly in the 10^12 TeV range. Or as I wrote earlier, such energetic collisions instantly kicked any possible initial 'false' vacuum in to the 'true' vacuum way back there and then. Either way, we concur there is no need to wait in fear.
     
    Last edited: Mar 28, 2015
  20. rpenner Fully Wired Valued Senior Member

    Messages:
    4,833
    No, there wouldn't. Collisions preserved total energy (a scalar quantity) and momentum. Thus two 100 EeV protons hypothetically colliding head-on in nature (a rare event) results in a proliferation of matter and antimatter, totaling to 32 Joules most with lots of momentum in all directions (so it sums to zero). But two 7 TeV protons (the LHC design) colliding head-on only have an energy budget of 14 TeV or 0.000014 EeV or 2.14 µJ. That's the energy needed to lift a dime (smallest US coin by mass) 0.1 mm. But since physics is local and protons are composite, only about 10-30% of that is available for probing new physics of parton-parton collisions.

    That type of collision is routine in nature, because 0.000007 EeV protons are much more common in cosmic rays than 100 EeV ones. But those natural collisions happen at times and places not of humanity's choosing. The LHC is designed to make such events happen frequently inside massive and sensitive detector complexes so we can precisely test theory against observation. It's nowhere close to precise enough to hit exactly one pair of protons together, rather the system is engineered to move clumps of them around and highly focus them into a collision area and even then most of the interactions are "near misses" which result very boring reactions that software eliminates for further consideration.

    Pb nuclei have over 200 nucleons so consequently they are less useful for probing new fundamental physics. But they do provide good laboratories of studying very hot bulk matter, including how quark-gluon plasma cools to form baryons.
     
  21. OnlyMe Valued Senior Member

    Messages:
    3,914
    Q-reeus, I was talking about total energy released, not just the kinetic energy of the two particles or ions.

    The rest was not directly in response to your post and I should have either made that clear or split the post into two.
     
  22. OnlyMe Valued Senior Member

    Messages:
    3,914
    Rpenner, I don't disagree with any of the above. Perhaps I am or have been a bit confused... Are you suggesting that there is no potential energy exchanges other than the initial kinetic energies? I have always thought that in addition to the kinetic energies, there were fission/fusion transitions involved in particle and heavy ion collisions. Very small and in some respects conserved in the formation of short lived exotic particles...

    Am I incorrect in interpreting the following, as involving energies in excess of the initial kinetic energy of the ions, essentially potential energies released as a quark-gluon plasma and then conserved, as the plasma cools and reforms baryons?

    Still your end conclussions seem to be consistent with the statement that the LHC is not producing collisions with greater total energies than occurring, even if rarely, in nature. That was and has been my intent.
     
  23. rpenner Fully Wired Valued Senior Member

    Messages:
    4,833
    Essentially, yes. The potential energy of a lead nucleus is negative with respect to free protons and neutrons.

    A Pb-208 nucleus actually has less energy than a collection of 82 protons and 126 neutrons. Thus if you fuse a Pb-208 from the 208 parts, the equation doesn't balance unless you add the kinetic energy (usually released as gamma rays) on one side of the equation.

    82 protons + 126 neutrons ⇌ Pb-208 nucleus + 1.6364296 GeV
    82 × ( 1 amu × c² + 0.0072889706 GeV) + 126 × ( 1 amu × c² + 0.00807131714 GeV) = ( 208 amu - 0.021748074 GeV) + 1.6364296 GeV
    Both sides are equal to 208 amu + 1.61468154884 GeV
    ( 1 amu ≈ 0.931494 GeV/c² which is based on \(^{12} \textrm{C}\) and here is used as a bookkeeping aid because relative energy-levels/masses are easier to get precise than absolute masses)

    Consequently, you have to add energy to tear a lead nucleus apart. That's what colliders are for. \(\gamma - 1\) represents the ratio between kinetic energy and rest energy.
    Assuming lab frame gamma of \(\gamma_{Lab} = 3000\), in either nucleus's rest frame it is minding it's own business when another lead nucleus (at \(\gamma_{Lead} = 2 \gamma_{Lab}^2 - 1 \approx 18000000\) ) smashes into it. So from both the lab frame and the nucleus' viewpoint there is certainly enough energy to tear it apart.

    (That trick is also why two 7 TeV protons striking head-on or one 100 PeV proton striking one at rest are both described as √s = 14 TeV events. http://en.wikipedia.org/wiki/Mandelstam_variables )

    The resulting cloud of quark-gluon plasma is filled with hot phenomenology of the Standard Model, and scatters to the four winds as a fireball without a chance of a heavy nucleus assembling from the nearly light-speed wreckage. So the Pb's binding energy only contributes negatively to the total energy of the debris, and in any case is completely dwarfed by the kinetic energy given the nuclei by the collider.
     
    hahnaz likes this.

Share This Page