Talk:Relativistic Heavy Ion Collider

Units of luminosity

It doesn't do much good to include a link in "a luminosity of 2 × 10²⁶ cm^-2 s^-1" when nobody in the luminosity article has figured out the strange units of particle physics. Will somebody who understands that please fix it? Gene Nygaard 12:10, 26 Apr 2005 (UTC)

Hopefully fixed now --Ylai 12:10, 12 July 2005 (UTC)

What's so relativistic about this thing?

Hello,

the article explains nowhere what the "relativistic" in the name refers to. If you are a physicist able to do this, please feel free. -- 84.130.24.229 17:32, 19 October 2006 (UTC)

I am not a physicist, but I believe that the term "relativistic," in this sense, refers to the fact that the ions in the reactor are accelerated until they are travelling very close to the speed of light. This is because objects travelling close to the speed of light experience the unique effects described by Albert Einstein's Special Theory of Relativity. For instance, the mass (M) of the ions increases as they approach the speed of light, because doing so involves a massive increase in energy (E), and Special Relativity teaches us that E=MC^2. The term "relativistic" is hyperlinked to the page on Special Relativity in the first paragraph of this article, I think. That should provide a much better explanation than mine, which likely contains a number of errors.

Hyperion35 20:07, 9 February 2007 (UTC)

Very interesting and meaningful questions about safety

A good discussion can be found in Richard Posner, CATASTROPHE: RISK AND RESPONSE, Oxford University Press, 2004. He includes the following two estimated risk possibilities (p. 141):

1 in 500,000,000 risk per year of a strangelet disaster, which is the highest estimated risk by Arnon Dar, A. DeRujula, Ulrich Heinz, “Will Relativistic Heavy-Ion Colliders Destroy Our Planet,” 470 Physics Letters B, 142, 146, (1999).

1 in 5,000,000 risk per year of a strangelet disaster, which is the highest estimated risk by R.L. Jaffe et al., “Review of Speculative ‘Disaster Scenarios’ at RHIC,” 72 Reviews of Modern Physics, 1125, 1126, (2000).

A strangelet is a very dense object composed of strange quarks that could, theoretically, if stable, if negatively charged, maybe, possibly, convert all atoms it comes into contact with into strangelets in a runaway process. Or, these other atoms might develop an outer shell around the strangelet that’s positively charged and thus repellant to other nuclei and thereby stop the process. We do not really know.

Now, with the two estimated risks, if we take 1 in 50,000,000, which is the order of magnitude between the two of them, well, in any kind of personal choice, a chance of getting cancer, a chance of being in an accident, 1 in 50,000,000 is nothing, just completely ignore it. It’s an absolute piece of cake. But, when we’re talking about the destruction of the planet, it’s not immediately obvious that 1 in 50,000,000 should be ignored, and that is the crux of the issue. How should we proceed? How do we go about making any kind of decision at all?

As our article points out, the Moon has been bombarded with cosmic particles of significantly higher energy than RHIC, and the Moon has not converted into a dense strangelet ball fifty meters across, and the Moon is almost as old as the Earth. So, we can breath some sigh of relief. But, when you have a worry and you look for a peg to hang your hat on to be absolutely sure, it never quite works out. There’s always some little glitch. Posner talked about the Moon (p. 193), and it’s different types of collisions! On the Moon, a cosmic particle would be slamming into a stationary particle and thus both would be pushed forward and have less chance of interacting with nearby particles. At RHIC, two particles will be colliding head-on and will be stationary for a longer period of time. How much difference? Who really knows. I suggest that we find another way to approach the question.

And we might start here: Most questions in ethics are far more profitably pursue as a How, than as an If. We humans are exploratory. It’s part of what makes us who we are. We are going to explore the Universe, including the fundamental sub-atomic components. The question is, How? FriendlyRiverOtter 07:24, 2 June 2007 (UTC)

A common solution, and perhaps a better one

I would like to be crystal clear about two things. First off, Richard A. Posner is not a physicist. He’s a federal judge! He has also written such books as LAW, PRAGMATISM, AND DEMOCRACY and AGING AND OLD AGE. So, he’s an intellectual guy. He likes to explore stuff other than the cases than come directly before him, and it probably makes him a better judge. (I recall that former Supreme Court Justice William O. Douglas liked to travel, he wrote and published books, I think at one time he even sold photographs to National Geographic, all of which probably helped him be a better judge.) And so, even though he does include copious references, Judge Posner is not an expert, but then, who really is? For this is not just physics, this is large issues about which risks are worth taking, which risks are not, and how to take the risks that are worthwhile. And that’s the critical question, How?

Now, the second thing, which was included above, but which I would like to emphasize, is that the number given for both Dar and Jaffe is the worse number, it’s the highest realistic risk estimate. A more “average” number might be one in two billion. But even with that, it’s the same issue. It is not immediately obvious that we should ignore a risk of 1 in 2,000,000,000 when we are talking about the destruction of the planet. Basically, we have a situation in which a very small number is being multiplied by a very large number, and that is a hard situation.

I’m going to include a quote from Posner, pages 191-92.

"Kent included in his risk assessment the threat to extremely remote future generations from an extinction event, without any discounting. He calculated that, barring disaster, the total number of human beings inhabiting the earth (not at one time, of course) between now and when the sun expands into the earth’s orbit may reach 10^17 (100 quadrillion). But he cannot prove--no one can--that we should worry about the survival of the human race over such a long span of time. Notice that if we do worry about it, not only does the cost of a strangelet disaster if it occurs soar, but the probability of the disaster, assuming that equally dangerous accelerators succeed RHIC for the indefinite future, rises. Even if the annual risk of a strangelet disaster is only one in a billion, the probability that such a disaster will occur in the course of the next billion years is 63 percent--though long before that time is up science may have learned how to avert such a disaster, and so the probability estimate may be far too high.

"Risk assessment is a seriously incomplete guide to decision making. . . ."

He cites Adrian Kent, “A Critical Look at Risk Assessments for Global Catastrophes,” 24 Risk Analysis 157, 161 (2004).

See also . . . http://arxiv.org/abs/hep-ph/0009204

So, 100,000,000,000,000,000 human beings. That’s a lot of people! Now, it is for the entire future history of the earth, and in a curious coincidence, we’re about midway through. The solar system has existed for about four and a half billion years, and it’s estimated to continue in present form for approximately another four and a half billion. So, you can figure the math if average lifespan stablizes at 120 years, and the population stablizes at . . . whatever (maybe we can come up with creative arranagements of co-parenting and convince people you can have all the fun of children, without having so many children yourself). And plus, if the average quality of life is good, why not a lot of people!

On the question of discounting, no, not like money, not merely because it’s a long time in the future. For if that person does exist, his or her life will be just as valuable then as yours and mine are now. But discounting for uncertainty, now that is more reasonable. For, like our article says, something else from space might wipe us out, or a natural epidemic (and there only has to be the first time, Posner, pages 21-24), or something we make ourselves. In fact, there are so many risks, that the inclination is to merely throw one’s hands up into the air. But it’s so much better to confidently address each one as it comes along with middle courses of action, and that’s what I’d like to advocate.

And our strength is not planning a sequence of ten steps deep into the future. Our strength is in improvising. So why don’t we play to strength? I think we should. The goal could be that the individual researcher could dance ever so gently back from the edge (and like a lot of good decisions, it’s as much a question of feel as logic), and with the level of informality to support this. In fact, the formality—the study groups, the published papers—would be to support this, much like a good poker player, who might well read books and work out odds, which does help, but at game time, it’s a question of feel. And a doctor, one who’s a skilled and experienced diagnostician, it’s primarily a question of feel. Someone trying to decision-tree it out, that’s likely to be a young doctor trying to get it “right,” and who may very well end up making a clunky decision.

So, the common solution is cost-benefit analysis, only (this time!) we’re going to get it right. The better solution might be to trust and develop your instincts. And by all means, examine studies, participate in studies, but toward the goal of better instincts. That is, I’m advocating right-brain, or whole-brain, rather than strictly left-brain FriendlyRiverOtter 08:11, 6 June 2007 (UTC)

please include a diagram

I think section 1 (the accelerator) should include a diagram in the part of the article talking about the overall operations of the accelerator. Does anyone have one? --WhiteDragon 08:54, 18 June 2007 (UTC)

After reading the article more carefully, I did see the link to a diagram on bnl.gov, but their image licensing policy [1] is clearly incompatible with the GFDL, so my original question still stands. --WhiteDragon 09:05, 18 June 2007 (UTC)

In addition, it appears that this article includes several images from the same website (bnl.gov) tagged as works of the federal government, so perhaps that would apply to the diagram as well. --WhiteDragon 09:17, 18 June 2007 (UTC)

Is it the most powerful?

The section titled The Future states that the RHIC is the most powerful collider in the world. However, the article states that the RHIC briefly achieved a collision energy of 400GeV, but typically operates at 200GeV. The Tevatron at Fermilab, on the other hand, operates at energies around 1 TeV, according to its wikipedia entry. Therefore, the claim in this article should be qualified by stating what measure is used to determine 'most powerful', as it is obviously not the measure of collision energy in eV, or the 'most powerful' claim should be removed. Harperska (talk) 23:17, 2 February 2008 (UTC)

I had the same question and marked the 'most powerful' claim as an unsourced statement. If there is a distinction to be made between power and energy, the issue is only confused further by the comparison of RHIC's power with LHC's energy. Gblandst (talk) 22:40, 22 August 2008 (UTC)

What's more, although the LHC will be more powerful than the RHIC when it begins colliding lead nucleii, as far as I know that won't happen for a while yet, so the statement 'At present, RHIC is the second most powerful heavy-ion collider in the world behind the LHC, which began its operation September 10, 2008' is not entirely accurate. I'm not entirely sure how best to rephrase it, though. --Angelastic (talk) 16:06, 14 September 2008 (UTC)

Split article

Anyone object to making the "Fears among the public" section (and related discussion) into a separate article (linked from main) ? Any better name than "Relativistic_Heavy_Ion_Collider - Fears among the public" ? Rod57 (talk) 15:10, 7 December 2009 (UTC)

That section is rather short to become its own article, what's wrong with having where it is now? If anything I'd merge it with the LHC crackpots article to make "Particle Collider Doomsday Theories" or something. – Joe N 21:53, 7 December 2009 (UTC)

Trivia section?

Would a trivia section be the right place to list things like "how much electricity the RHIC uses at peak power, compared to a household, city or nuclear power plant", "how much gold gets destroyed per second or day", "the width of the beam", "exactly what would happen to a person left in the tunnel", and probably a lot of other things? The idea came about when I tried to understand the beam luminosity by multiplying it with Gold atomic mass and Molar mass: 2×10^26 * 197 * 1.66×10^–27 = 65.4. This would mean that if the beam is one centimeter square then RHIC uses 65 kilograms of gold per second. So either the beam is incredibly thin or I'm grossly mistaken here.

As an aside, the beam luminosity is of course an important number, but the public would probably want to see it in absolute terms rather than per cross section area, i.e. how many atoms per second. Gwrede (talk) 17:26, 3 March 2010 (UTC)

How much does it cost?

We are never told the costs of these things. No doubt the figure is approaching 'relativistic'. It must be Economically very proficient at generating Income for not only Scientists, but also cutting-edge Heave Industry. As high income earners with modest life-styles, the proportion of Income saved will be higher than average, creating National Wealth. For most countries it depends on no foreign spending but for the USofA it remains in dollars. The Economic consequences of Scientific Work is generally ignored, but must surely be as important as the actual Physics, especially in a real-world, practical sense and not just theory. Or am I too much of an empiricist? I don't know where on Wikipedia to write these things or get comments and hopefully agrement on making the articles better. The conversion of muscle-chemical energy and other forms via Work into Financial Energy or Pecuniary Energy is ignored, so far by Physicists. NaumTered (talk) 21:10, 20 October 2020 (UTC)