How Safe is the LHC?

All of this has happened before, and it will all happen again. –Peter Pan

Much like any new venture where the outcome is uncertain, there are a lot of fears surrounding the LHC. And I know, because it occasionally shows up in my comment threads, in my inbox, or in my office.

Could it form a black hole and destroy Earth? Could we somehow do something in the future that would destroy the past? Or is it just generally unsafe?

The answers to these questions are no, no, and no. The first question — about creating a black hole and destroying Earth — requires that we apply the laws of physics and work out just what will happen in different physical scenarios. It’s a good scientific question, because we can answer it scientifically. I did this myself, and have concluded that there is no chance of the Earth being destroyed.

But the other two questions really fail to appreciate how science works, in my opinion. We have collided literally many trillions of particles at very high energies at particle accelerators over the past 100 years. Moreover, we are constantly bombarded by cosmic rays from space. Many of these have energies far in excess of (at least 10,000,000 times greater than) anything we will be capable of doing at the LHC. In other words, the LHC will not create anything that has not been created on Earth many times before.

But the new thing is that we will create it in a controlled environment where we can measure and study it. In other words, we get to do science on it. Instead of things merely happening around us (and to us) by chance, we can determine when and where they happen, and learn about it.

Yes, we will be studying energies that we haven’t been able to study before, but we have a long way to go before we get up past energies that commonly occur on Earth. It’s exciting to probe this new realm of physical reality, but it isn’t threatening. We will not be unlocking new forms of hungry energy, time-anomalies, or other doomsday phenomena. The Universe makes things far more powerful and energetic all the time than we ever have, or than we ever have plans to do.

But when we pass that, when energies reach about a factor of 100 stronger than the LHC can, then these will be legitimate questions to ask. But there are no worries now. And if you have them, you can leave them in the comments, and if there are any that are legitimate, I’ll write about them! Until then, the storage of all that liquid helium is far more dangerous than anything that will come of collisions taking place at the LHC.

Comments

  1. #1 Robert
    October 15, 2009

    Please provide reference to document constant bombardment of cosmic ray energies 10,000,000 times greater than anything LHC is capable of doing. I can’t find anything close to that.

  2. #2 Ethan Siegel
    October 15, 2009

    Robert, they’re called Ultra-High Energy Cosmic Rays. While the LHC energies are typically around 10^12 to 10^13 eV, the UHECRs are routinely in excess of 10^19 eV. Check out this paper from 2002: http://arxiv.org/abs/hep-ph/0206072

  3. #3 Robert
    October 15, 2009

    Good article. Thanks!

  4. #4 Katherine
    October 15, 2009

    This sort of topic is one I am certainly happy to leave to the experts. I’ll watch out for myself as I cross the street or ride in a car, you guys can make sure you don’t blow up the planet.

    And the newspapers will try to create a panic. Bleh.

  5. #5 Ross Bradley
    October 15, 2009

    Hi,
    It never ceases to amaze me at how much credence the popular media can give to the fringe elements who would try to stop the LHC. I think they would prefer a sensational beat-up to accurate reporting.

    Anyway… I’m don’t have a scientific background, but am interested in science and I do read some popular literature and have a couple of questions that maybe you could answer (or point me to a site/text).

    1. Neutrinos: I’ve read of the solar neutrino problem and its resolution with the neutrino oscillation theory, but what I don’t get is that if neutrino’s travel at the speed of light, how do they experience time to oscillate in? – and how can something with mass travel at C – wouldn’t it’s mass become infinite?

    2. Equivalence of Gravity & Acceleration. If gravity transmitted by gravitons and, according to GR, a gravitational field and acceleration are equivalent, where do gravitons fit in with acceleration?

  6. #6 Steinn Sigurdsson
    October 15, 2009

    Ethan – you need to account for conservation of momentum, the UHECR energy is not all available for particle creation, you need to go to higher energies to compete with the LHC

    That said, Hut and Rees pointed out many years ago that particle colliders would not trigger phase transitions or black hole formation based on a full calculation of the cross-sections and fluxes of the very highest energy cosmic rays, assuming GZK limit holds.

  7. #7 Nathan Myers
    October 16, 2009

    If it can’t destroy the Earth, what the hell good is it?

  8. #8 Naked Bunny with a Whip
    October 16, 2009

    if neutrino’s travel at the speed of light, how do they experience time to oscillate in?

    You have that the wrong way around. If neutrinos oscillate — as they appear to — then they do not travel at the speed of light and therefore have a small rest mass.

    where do gravitons fit in with acceleration?

    I don’t think there’s a working theory of where gravitons fit in anywhere right now. Also, the Unruh effect may break the equivalence principle. Neither gravitons nor Unruh radiation have been observed, AFAIK. (Unruh radiation is controversial.)

  9. #9 David
    October 16, 2009

    It might however create a financial black hole which exerts an irrisistable pull on science budgets, but from which no knowledge can escape. With proper public relations management it can then be called a “spinning black hole”

  10. #10 The Backpacker
    October 16, 2009

    Oh come on David, as long as they can keep the gremlins way from the coolant seals the worst thing that could happen would be that it would confirm the theories we have been working with for the fifteen or twenty years. I am not a physics person but I don’t think that is going to happen. You never know where experiments can take you. And if nothing else it is really shiny so cheer up…. shiiinnnnyy

  11. #11 ScentOfViolets
    October 16, 2009

    That said, Hut and Rees pointed out many years ago that particle colliders would not trigger phase transitions or black hole formation based on a full calculation of the cross-sections and fluxes of the very highest energy cosmic rays, assuming GZK limit holds.

    I thought the ‘fix’ was that there are branches of the wave function where the universe is destroyed by a phase transition; we’re just not present in those worlds ;-)

  12. #12 Jim Bob Cooter
    October 19, 2009

    “And if nothing else it is really shiny so cheer up…. shiiinnnnyy”

    And we all know that this is how financial institutions decide when and how to bestow loans upon us cretins:
    http://www.wigu.com/overcompensating/2005/11/catbank_04.html
    (links to webcomic with a Scary Bad Word in it, for those of you at work)