LHC - Big Bang or Every Day Gamma Ray?

September 13, 2008 11:48 AM

Okay, I know there have been 2 other questions recently about LHC, but both threads seem to have died. I have a question that I haven't seen answered anywhere else yet: 1) I have read quite often that LHC will create "energies not seen since the Big Bang." 2) I have also read frequently that "gamma rays magnitudes of order more powerful strike the earth regularly." So which is it? It seems to me those two statements contradict each other. If the former is true, how does the 2nd one jive with the first? If the first is true, why shouldn't we be concerned, unless the second is true, in which case, isn't the first statement false?
posted by PigAlien to science & nature (11 comments total)

The LHC will be colliding two beams of protons each of ~7 TeV. Ultra-high energy cosmic rays have been observed with energies approximately 10⁶ times that.
posted by kickingtheground at 12:26 PM on September 13 [1 favorite]

Each beam of protons is comprised of packets with 10's of billions of protons each. Each cosmic ray is just one particle. The intensity of collisions at the LHC will be higher than the decay events of cosmic rays.
posted by fatllama at 12:36 PM on September 13

Hi Kickingtheground, that is a straightforward answer that is easily understandable. However, what about the claims that the LHC will create energies not seen since the Big Bang? Is this just complete nonsense being spouted by ignorant media outlets? If that is the case, then answer seems to be that idiots are out there making completely ridiculous claims. I'm almost embarassed the answer should be so simple, but then its clearly so present in the media as to be scandalous if its simply not true.

In follow-up to my own question, I did a google search and found the following blog post addressing exactly my question:

http://backreaction.blogspot.com/2008/07/recreating-big-bang.html

I'm tempted to delete this question, but then I think it might be helpful to others wondering exactly the same thing as myself.
posted by PigAlien at 12:38 PM on September 13

Thank you for your reply, fatllama. By intensity, do you mean the rapid-fire frequency of collissions (each one still small compared to a gamma-ray collision), or the actual energy given off by each individual collision in the LHC? If you mean the energy given off by the individual collisions, how does that support the argument that gamma rays strike the earth all the time? Or am I mixing apples and oranges somehow?
posted by PigAlien at 12:41 PM on September 13

By intensity I mean brightness. Of the 10's of billions of protons per packet, only 20 or so will experience a collision per beam crossing. The beams will cross 40 millions times per second. So they will observe perhaps 800 million collisions per second.

That rate of high energy events is what has not been seen since the big bang. I agree the PR statements are somewhat conflicting.
posted by fatllama at 12:53 PM on September 13

Thank you, fatllama, its very patient and kind of you to try and tease out the inaccuracies in the reporting for us laymen!

That's quite interesting to know.

In regards to your second sentence, can we even say that accurately? Besides the obvious conjecture that other sentient life forms may have created unimaginable amounts of high energy events long before us (hahaha), if we stick to what we know, wouldn't a gamma ray burst event vaporize anything nearby, such as entire planets and stars, not to mention interstellar dust on scales much larger than this? Wouldn't an entire planet being vaporized cause more than 800 million collision per second?

Forgive me if I'm totally off-base with this logic.
posted by PigAlien at 1:02 PM on September 13

Has not been seen by us is the rather simple answer to your question.
posted by knapah at 1:07 PM on September 13

Well, I think the simple answer, knapah, is that the media are to blame, and perhaps even some of those scientists working with the media. Obviously, to say "has not been seen by us" is not accurate because we did not see the Big Bang either. Those who make statements such as "biggest energies since big bang" are only supposing, not speaking from the standpoint of concrete information. In fact, upon further thought, it seems quite easy to conjecture many situations in which such energies have been created since the big bang. Certainly a supernova must give off far more energy than the LHC and far more intensely, or am I just totally wrong? Could it truly be possible that we are capable of creating energies greater than a supernova?
posted by PigAlien at 2:26 PM on September 13

Could it truly be possible that we are capable of creating energies greater than a supernova?

Yes and no - it's not about quantity energy, it's about how concentrated that energy is. Neither nuclear fission nor nuclear fusion nor a nuclear bomb can produce particles as energetic as LHC, yet a nuclear bomb unleashes vastly more energy far more violently. A big explosion doesn't necessarily mean the particles have a lot of energy concentrated in each, just that there is an awful lot of energy - which could just mean an awful lot of low-energy particles carrying that energy.

From a brief look on the web, it sounds like supernovas are theorized to be able to result in more energetic particles than the LHC, but not really because of their explosive force or massiveness;
Supernova shockwaves could harbor intense magnetic fields for thousands of years, and particles could bounce around in the magnetic fields like in a pinball — sometimes long enough to gain high energies. But not high enough: Most astrophysicists think it’s unlikely that a supernova could produce cosmic rays above 10¹⁶ electron volts or so.
It's an article about the high-energy particles from space that you mention, you might find it interesting.
But going by that figure, the upper limit on what a supernova could produce, is:
100,000,000,000,000,000eV
The most energetic collisions in the LHC will initially be about:
1,150,000,000,000,000eV
However the LHC is expected to be upgraded after ten years, for higher energy collisions. I'm not sure how much higher.

But more energetic particles yet are known to occur in nature, meaning they presumably don't come from supernovas. Details in the article.


As to "energies not seen since the big bang", the phrase I've heard is "recreating the early moments just after the big bang", which unlike the "energies" phrase, seems quite reasonable and accurate. So I think people have just been inadvertently mixing their (non)metaphors.
posted by -harlequin- at 3:05 PM on September 13

My understanding: Immediately after the "big bang", the universe was extremely hot/energetic. It has been cooling/expanding ever since. The LHC allows us to observe particle interactions at energies that would have been the norm at a tiny instant after the big bang occurred. Great for understanding how the universe got started and just how it works in general.

The key point is that it allows us to observe those events -- meaning that it makes enough events of high enough energies that over time we can gather enough information to piece together what things were like at big bang + epsilon.

Other than the above, the idea that this is anything novel in the universe since the big bang is just media BS. It's a big universe. Those cosmic rays come from somewhere. Quasars are out there. Gamma ray bursters are out there. Many things that as far as we can tell are preposterously energetic, and many more that we can't really explain at all. Heck, throw in aliens that are working on their equivalent of LHC-2 and beyond, etc, etc, etc.
posted by madmethods at 3:13 PM on September 13

Well, I think I would mark several of the answers as best answers here in combination, but since I can't, I won't mark one. I really appreciate that you all contributed something positive. I think it took a bit of back-and-forth to get me to a better understanding, but I think harlequin and madmethods sum it up nicely. Thank you everyone!
posted by PigAlien at 3:25 PM on September 13