The news that the faster-than-light neutrino results announced to such widespread interest by the OPERA collaboration have now been explained has been spreading irresistibly around the Internet. But the brief piece in ScienceInsider that broke the news was stretching a point with a lead reading “Error Undoes Faster-Then-Light Neutrino Results.” For when you read the story, you see that a fiber optic cable connection is a possible culprit, though as yet an unconfirmed one.
Sean Carroll (Caltech) blogged on Cosmic Variance that while he wanted to pass the news along, he was reserving judgment until a better-sourced statement came to hand. I’ve thought since the beginning that a systematic error would explain the ‘FTL neutrino’ story, but I still was waiting for something with more meat on it than the ScienceInsider news. It came later in the day with an official CERN news release, and this certainly bears quoting:
The OPERA collaboration has informed its funding agencies and host laboratories that it has identified two possible effects that could have an influence on its neutrino timing measurement. These both require further tests with a short pulsed beam.
So we have not just one but two possibilities here, both with ramifications for the neutrino timing measurements and both needing further testing. And let’s go on with the news release:
If confirmed, one would increase the size of the measured effect, the other would diminish it. The first possible effect concerns an oscillator used to provide the time stamps for GPS synchronizations. It could have led to an overestimate of the neutrino’s time of flight. The second concerns the optical fibre connector that brings the external GPS signal to the OPERA master clock, which may not have been functioning correctly when the measurements were taken. If this is the case, it could have led to an underestimate of the time of flight of the neutrinos. The potential extent of these two effects is being studied by the OPERA collaboration. New measurements with short pulsed beams are scheduled for May.
Image: Detectors of the OPERA (Oscillation Project with Emulsion-tRacking Apparatus) experiment at the Italian Gran Sasso underground laboratory. Credit: CERN/AFP/Getty Images.
We may well be closing on an explanation for a result many scientists had found inconceivable. Here’s a BBC story on the possibility of trouble with the oscillator and/or an issue with the optical fiber connection. We learn here that a new measurement of the neutrino velocity will be taken in 2012, taking advantage of international facilities ranging from CERN and the Gran Sasso laboratory in Italy to Fermilab and the Japanese T2K. The story quotes Alfons Weber (Oxford University), who is working on the Minos effort to study the neutrino measurements at Fermilab:
“I can say that Minos will quite definitely go ahead… We’ve already installed most of the equipment we need to make an accurate measurement. Even if Opera now publish that ‘yes, everything is fine’, we still want to make sure that we come up with a consistent, independent measurement, and I assume that the other experiments will go forward with this as well.”
So this is where we are: An anomalous and extremely controversial result is being subjected to a variety of tests to find out what caused it. If I were a betting man, I would put a great deal of money on the proposition that the FTL results will eventually be traced down to something as mundane as the optical fiber connector that is now the subject of so much attention. But we’ll know that when it happens, and this is the way science is supposed to work. OPERA conducted numerous measurements over a three year period before announcing the FTL result. Let’s now give the further work time to sort out what really happened so we can put this issue to rest.
I’m already seeing headlines proclaiming that the neutrinos may be moving even faster than originally reported. A sensationalistic media will tend to accentuate (cherry pick) the one aspect of a factually-balanced report that will attract the most eyeballs.
Don’t want be sarcastic, but to me it looks like a “we found what was the mistake, and it was a silly one, can we really say to the world it was as simple?, no, let’s take time to release it”. Remember how fast they made their second measurement with shorter pulses, confirming the time delay. I mean, we are all human, and this is a very very big experiment with so many people onto, that each one can’t be aware of everything, it sure was an error. We all hope for such breakthrough, but we can not create it thinking nobody will never be able to check it by himself. I really think in a lot of researches people almost think like that, let’s try, we worked hard with good tools, and good theory from the books, scholarly, so we can publish our results. A lot of people publish results without any concern of theoretical contradictions. cutting edge science is border line science sometimes.
This is what I said back on the Sep. 23, 2011 posting about the initial announcement on possible FTL: “I think the distance measurement is probably pretty accurate. But how do you ensure the timing is accurate? If the particles traverse a one-way flight, do they use two clocks, one at the start, and one at the end? How were they synchronized? How was the synchronization verified? …”
Seems like they asked themselves some of the same questions, perhaps in much greater detail, and uncovered the potential mechanisms for error and likely culprits. Not surprised by this result. It serves as a good example of how tricky leading edge science can be. I’m still hoping near-light-speed or even FTL technologies can be developed and employed for exploration some day.
Before you all get too excited, I will again remind you all of that 5 neutrino burst from the direction of the Large Magellanic Cloud that hit the LSD under Mont Blanc 5 hours before the main wave of neutrinos from SN1987a.
I can’t help noticing that there has never been any experimental evidence that was consistent with a subluminal neutrino speed, and that includes at least five different double beta decay measures of its mass as imaginary, and none that measure it as real.
I have a novel idea. Why not test these findings with further experiments, rather than endlessly retrofitting data to models already done (and to date that includes trimming valid data from a set so that they may fit conventional slower than light models). Why not start speculating on the design and nature of these new experiments rather than what might be wrong with the old.
Sorry if that is harsh, I do understand that you are afraid of spending money time and effort on a problem that so many others expect to evaporate, But to me fear of potential embarrassment is the strongest break on progress due to a surmountable human flaw. Get over it!
We learned two things with this:
1) How good scientists conduct experiments (test, observe, retest, observe, announce findings and get others to test, observe, etc..)
2) A LOT of people are interested in anything that has to do with possible FTL, no matter how slim the possibility. Our Hope-meters jumped, even though we all suspected it would be proven wrong.
Maybe next time!
“…I do understand that you are afraid…”
Who is this ‘you’ that you are talking to?
Ron S asks to whom I was addressing my comment, and the answer is all who spend more time speculating on the faults of the old experiments than they do on the design needed for a new experiment. Because the nature of the above article is more likely to elicit opinion on the former than the latter, I can only guess who this might apply to.
To me the whole FTL story has adifferent meaning . It shows how strong the urge to maintain the illusion of certainty , even when dealing whith things close to the edge of the acuracy of obtainable results . In the border areas betwen solid knowledge and a beatiful theory , we have to accept the need to define a Working Hypotesis without dressing our asumptions up as TRUTH.
The Idea that FTL is impossible remains our working hypotesis , a tool necesary to moove on , a tool that might evetualy help to proove itself wrong .
Doesn’t mean they were superluminal. An earlier episode of neutrino production in the supernova is another possibility.
Formal best-fit values are negative yes, but the error bars on recent measurements certainly allow for positive neutrino mass-squared.
Obviously if an experiment gives a result Rob Henry likes, particularly if it is a completely unexpected result in the framework of physics that has stood up to numerous rigorous test before, it must be correct and any attempts to rigorously scrutinise the experiment are a waste of time.
After all, it might show that the conclusion that Rob Henry likes is incorrect, and we can’t have that can we?
Spoken like a true believer. Anyone who is sceptical about FTL must be “afraid”, because Rob Henry wants FTL and he is perfectly happy with the results.
andy
“Spoken like a true believer.”
I can say this about you; you ‘beleive’ AKA are convinced without proof that the neutrino is not FTL.
Why ‘without proof”? Because it was never proven that the neurino is slower than light; in this area, relativity’s assertion is merely an uunproven conjecture which did not pass rigorous tests before.
My pont is not primarily about the neutrino’s speed.
It’s about the type of mindset you (and many others) showed to have – which, in my opinion, is not amenable to scientific progress; it has too much in common to religious dogmatism (easy acceptance of the conjectures supported by the witings of Einstein, Bohr and the other giants and easy rejection of all the others) to the detriment of scientific scepticism.
“My pont is not primarily about the neutrino’s speed.
It’s about the type of mindset you (and many others) showed to have – which, in my opinion, is not amenable to scientific progress; it has too much in common to religious dogmatism (easy acceptance of the conjectures supported by the witings of Einstein, Bohr and the other giants and easy rejection of all the others) to the detriment of scientific skepticism.”
There was no ‘easy’ acceptance of Einstein and Bohr, lord!, there have been a 100 years of empirical support. That is the opposite of religious dogmatism.
If the approximate models we have in physics and biology used as applications were not true then people would not be making money off of them. For me money talks.
Andy, for me to believe that neutrinos were faster than light, I would have to take the paradigm approach to science, and I believe that to be an oxymoron. Science wins as soon as we take Socrates mantra of “I know one thing, that I know nothing”.
Of those 5 earlier neutrinos you write “Doesn’t mean they were superluminal. An earlier episode of neutrino production in the supernova is another possibility.” and I agree completely. I know of a couple of peer reviewed attempts to do so and, but unfortunately they produce such a poor fit to the data as to make them highly unlikely explanations. It is possible that one day a reasonable fit will be found with a conventional explanation, just as it is possible that neutrinos are ftl. What surprises is that this point is not also obvious to you.
@ Paul
I think we will just have to agree to disagree. In my stodgy old opinion, this is not how science should work. When you have a result that screams “systematic error” rather than “new physics” one has a responsibility to clean their own house before bothering the totality of the physics community (and public!) with a sensationalist announcement which has ended up by damaging scientific credibility. This was 21st century Facebook science, and I do not mean that in a good way… “OPERA has posted on their wall that pigs fly!…maybe”
Some of the OPERA collaborators felt the same way and refused to sign the September paper (although some of them were browbeaten into later signing the November paper). Some problems have to be chased by actual equipment technicians in coveralls rather than scientists. If the OPERA team did not have competent tech support, they should have brought in outside technicians from other neutrino centres for independent opinions. Rinse and repeat until every possible source of error is eliminated as impossible. Only then can one assert that the highly improbable is likely to be true. Much better than publishing a paper which amounted to an admission that they likely had an equipment problem, but were not competent to troubleshoot it. Even after the November (tight burst) paper, many others felt this way:
““I can now say that the probability of the result being correct has increased from 1 in a million to one in 100 thousand,” wrote physicist Philip Gibbs on the viXra log (though he stressed that those numbers were merely illustrative and not actual calculated values).” Peter Woit felt the same way.
@Daniel Suggs re: “Our Hope-meters jumped”
I really, really, really can’t wrap my head around why so many people, especially commenters on this blog, felt that emotion about this result. Even if it were true, suppose some flavour and energy of neutrinos really can move at c + a minute fraction (rather than the usual c – a minute fraction). So what? Good grief, if we were even made of ordinary neutrinos, we would be moving at nearly c anyway!
We and our machines are made of baryonic matter. General Relativity has never been our problem. Our current ion drives have an exhaust velocity of 1/10,000 of c. Not much gamma (Lorentz factor = 1.000000005) involved there. The fastest bulk movements of bulk baryonic mass observed in the universe (supernova debris and winds from black holes) are less than 5% of c. The most optimistic assumptions about He3+D fusion rocketry have a similar exhaust velocity of no more than 5% of c. Even fantastic dreams of bulk antimatter rocketry designs or high energy laser driven light sails cannot exceed 50% of c.
Ok, suppose the Vorlons show up and hand us some magical energy modules which can pull unlimited energy out of the ether. Then we could travel as close to c as one would like, and the Lorentz time dilation would make the subjective time of the trip as short as you would like. Even with magical energy sources from new physics, the c limit is completely irrelevant as a barrier to space travel. At best this result could have been an imaginary solution to a nonexistent problem.
@A.A Jackson: “Unthinking respect for authority is the greatest enemy of truth.” – Albert Einstein
Actually Einstein’s special theory of relativity only disallows acceleration past light speed, or for a tachyon deceleration below light speed. I put it to you that your appeal to authority might be just a desperate attempt to up hold freewill from possible incursions, and, if so, has the pure religious motivation that Avatar2.0 posits.
Relativity has withstood an awful lot of experimental testing, and that history of experimental testing should not be dismissed lightly. Yes I believe that the neutrino is not FTL, because that is the overwhelmingly reasonable null hypothesis.
In science you come up with experimental results that contradict existing theory all the time, even to high degrees of statistical significance. The reason that we aren’t rewriting the fundamentals all the time is because of the following: systematic error. Systematic errors can be extremely subtle and are often a nightmare to eliminate. And often once you have managed to take them into account your groundbreaking discovery gets contradicted.
But hey, don’t let that stop you FTL true-believers from playing the oppressed Galileo card.
@Rob Henry
“Actually Einstein’s special theory of relativity only disallows acceleration past light speed…”
Actually this follows from the two postulates of special relativity:
(1) the laws of physics are the same in all inertial frames of reference.
(2) the speed of light in free space is a constant in all inertial frames of reference.
Really one could say acceleration of a particle past the speed of light follows from the fundamental postulates. The statement given above does not trump these.
These postulates have been tested in hundreds of ways.
I always thought Einstein should have gotten a second Nobel by 1930, since there was so much empirical evidence. However more so, because, P.A.M. Dirac combined special relativity and quantum mechanics to construct a model of the electron. Which turned out to predict the existence of the positron , which won Dirac a Nobel. Talk about a validation of special relativity and quantum mechanics in one shot!
I could never say it better than Wheeler and Taylor:
“The principle of relativity is used every day in many fields of physics where it is continually under severe tests. For example the Stanford Linear Electron Accelerator (estimated cost: $300,000,00) has to be two miles long to push electrons up to the speed that is almost the speed of light. If pre-Einstein Newtonian laws of mechanics were correct, then the accelerator would need be less than one inch long to produced electrons with the same speed!”
As for orthodoxy, Issac Asimov had the best:
“For the self-correcting structure works. There is a delay and heartbreak often enough, but it works. However grim and slow the self-questioning process of science may be (indeed, that the process exists at all is a matter of pride to scientist), science remains man’s only self-correcting intellectual endeavor.”
“…that is the overwhelmingly reasonable null hypothesis.”
I think you mean the ‘prior probability’ of the non-FTL hypothesis is high (close to 1). The null hypothesis is that the experiment determined nothing at all: neither FTL nor non-FTL hypotheses. The probability of the null hypothesis in this experiment appears to have been much higher than the other hypotheses.
A.A. Jackson, I admit that I really don’t understand you. You begin by dramatically understating the degree to which special relativity has been tested and matched expectations. Surely the high number of decimal places that experimentation has matched it to expectation deserves some mention!
You then continue by reiterating the speculation that nothing can go faster than light. If you know of some way that SR itself precludes tachyons, I would love to hear it, since in all the talk and papers I have read on them, most keep repeating how the concept itself springs specifically from SR. Not one treatment of their mathematics that I have ever read ever mentions a direct conflict with SR though often they talk of problems with Cheerenkov radiation and its non-electromagnetic equivalents.
On the other hand, if your real worry is just the standard interpretation of the way SR combines with quantum mechanics you should really limit you objections to that.
Actually A.A., I know that this is a bit off topic but I’m a little concerned over your two postulates for SR not including isotropy and homogeneity of space time and, for this exercise, let’s ignor GR. I can’t help but feel that there may be other ways to solve your two points given that extra leeway, even if none of them look remotely like our universe.
andy
“Relativity has withstood an awful lot of experimental testing, and that history of experimental testing should not be dismissed lightly. Yes I believe that the neutrino is not FTL, because that is the overwhelmingly reasonable null hypothesis.”
And none of this testing relates to the neutrino, andy. You cannot claim experimental backing for your belief.
There is experimental backing for the affirmation that the neutrino is FTL, though.
Your reaction – belief without proof in the writings of saint Einstein.
andy, theories until now were approximations – they work well in a certain range of values, until they become a special case of a more general theory. For example, Newton’s gravity and relativity.
You beleive relativity to be absolute – that anything that contradicts it must be wrong somehow. A dangerous and highly counter-productive mind-set; you delude yourself if you think this is a scientific mind-set.
The question I have on all this that I have not seen anything of substance on is, even if neutrinos could go FTL, how do we turn this into a starship propulsion system that goes FTL? Everyone half-jokes that we will be building warp drives in no time, but seriously, how would this result even if it were real be turned into something that would revolutionize technology, science, and humanity itself? And do we want our species in its current state hopping all over the galaxy at record speeds? And FTL travel is real, why haven’t we seen anyone more advanced than us zipping around in such a vessel?
About those neutrinos that appeared 5 hours before the main wave from Supernova 1987A – which, BTW, celebrated its 25th anniversary of appearing in our heavens on February 24: Do stars have some kind of “pre-shock” before the main explosion during a supernova event? Or perhaps just certain kinds of stars do this? Sanduleak -69 202 was a blue supergiant, if that has anything to do with this phenomena.
Quotiung from this online source here:
http://www.astrophysicsspectator.com/topics/supernovae/CoreCollapseNeutrinos1987a.html
“And now for the puzzle. A fourth detector measured a signal from the direction of the Large Magellanic Cloud, but the observation is out of line with the other-three detectors. The LVD detector underneath Mont Blanc, between France and Italy, saw 5 neutrino events 5 hours before those detected by the other three detectors. This detector is similar to the Baksan detector in design. The sensitivity of LVD is such that it should only see 1 neutrino from the supernova. The spurious time, the unexpectedly high count rate, and the inability of theory to easily account for such neutrinos cause most astronomers to doubt that this detector observed the supernova. The ambiguity generated by this measurement will persist until other supernovae are seen by neutrino detectors.”
BTW 2 FYI – I just learned that Voyager 2 imaged SN 1987A while on its way to Neptune.
Avatar2.0
but you do the same thing. you already accept that those neutrino go faster than light. extrodinary claims needs extrodinary evidence. you want this to be true because you think that we can than travel faster than the speed of light. Lets wait for the next result of the experiment and than we will see if those neutrino’s move faster than the speed of light and if that happen than let someone else confirm it. Than we can say that those neutrino’s move faster than the speed of light.
you need to understand why people are skeptical about it. lets see what those experiments will bring us.
what experiment beside cern said that the neutrino moved faster than the speed of light ?
@Avatar2.0
If as you claim I believe in the infallibility of Einstein, then I would have to reject the whole extremely-well-tested set of quantum field theories which are incompatible with Einstein’s general relativity. Which would be ridiculous because as I said these theories are extremely well-tested.
And that incompatibility between general relativity and quantum field theory means there must clearly be a hole in our understanding. Nevertheless from both sides of this we have extremely well tested theories, particularly in the case of the limit of special relativity which is built in to quantum field theories at the very base level. E.g. spin is a property that emerges naturally when you combine classical quantum mechanics with special relativity. Note that the very theory that describes the interactions that produce the neutrino fundamentally rely on special relativity.
There are certainly interesting experimental results that may or may not indicate physics beyond the standard model and beyond general relativity, but as yet nothing compelling once statistical uncertainty and potential systematic errors are considered (e.g. the neutrino mass squared measurements still allow for a positive value within the uncertainties). Until there is a compelling reason to reject the null hypothesis we should not jump to unwarranted conclusions.
Your mindset, that we should throw out the vast quantities of existing experimental data because, hey, you like the look of the result (FTL woohoo!) and want a nice Galileo vs the church narrative is far more antithetical to science.
Henk gives a plug for scientists doing the absolute minimum possible with “Lets wait for the next result of the experiment and than we will see if those neutrino’s move faster than the speed of light and if that happen than let someone else confirm it.” and Ron S has already pointed out “The null hypothesis is that the experiment determined nothing at all” and that is the best that conventional physicists can likely hope for.
In this case, conventional physics would place the neutrino speed so close to light that OPERA should have been unable to determine whether it was a tardyon or tachyon. It is my opinion that, considering other evidence, we need further testing on this matter as a priority anyway. To me this is just the latest wakeup call.
Henk also states “extrodinary claims needs extrodinary evidence.”, and I feel obliged to ask where this comes from. Is it:
a) a logical deduction, derived from the way statistics confidence levels must be readjusted to account for the current consensus;
b) an admission that once innovative and brilliant scientists become staid and moribund as they grow older and more prestigious.
If I was sticking strictly to logical and statistical principles that were known to me, a) would only have any purchase as far as a priori v a posteriori data fitting was concerned, and that is irrespective of consensus.
from ljk:
“The question I have on all this that I have not seen anything of substance on is, even if neutrinos could go FTL, how do we turn this into a starship propulsion system that goes FTL?”
Exactly my point above! There is no reason that one implies the other. We know that photons travel at c, but that hasn’t helped us build starships which can travel at c. Just some deeply irrational flights of fantasy taking off here.
“Everyone half-jokes that we will be building warp drives in no time, but seriously, how would this result even if it were real be turned into something that would revolutionize technology, science, and humanity itself?”
It wouldn’t. All that would happen is that the just barely FTL neutrino speed n would replace c in calculating the Lorentz factor. An adjustment of circa 10^-5 in our equation, and the behaviour of nature would still not be pleasing anyone any more than it does now.
“And do we want our species in its current state hopping all over the galaxy at record speeds?”
The question answers itself. In the past century on this little planet the elephant, gorilla, and tiger populations have dropped 95% while the scarcely studied Caribbean monk seal and Yangtze river dolphin have gone extinct. Tool using or not, ET life does not deserve to be mindlessly consumed by a violent swarm of human animals addicted to wasting nonrenewable resources in financial pyramid schemes and still unable to control their own reproduction.
“And FTL travel is real, why haven’t we seen anyone more advanced than us zipping around in such a vessel?”
Because FTL travel is not real. Reaching solar escape velocity is possible, we have been doing that for the past 40 years. Now we have to figure out how to keep machines carrying dormant biological material viable for passages of thousand of years. If this is possible at all, it could only be done by a species much more mature in outlook than ours.
Ljk’s question of the utility of tachyons towards increasing actual travel speeds is interesting. I remember reading an article that claimed that such a drive would be great for hovering at a static position within a gravitational field, but little else. I can remember that the argument and the mathematics used looked convincing at the time. I’m wondering if anyone knows the current consensus on this matter.
That one’s easy: Because there is nobody there (ducks) :-)
Always keep the Good Doctor in mind:
“I believe in evidence. I believe in observation, measurement, and reasoning, confirmed by independent observers. I’ll believe anything, no matter
how wild and ridiculous, if there is evidence for it. The wilder and more ridiculous something is, however, the firmer and more solid the evidence
will have to be.”
— Isaac Asimov
I can tell you why the findings made by Albert Einstein are not to be sneezed at: Because scientists have been hacking away at his ideas since the day they were first announced and they have withstood the onslaught.
Many people think that science and scientists, like SETI, are this monolithic structure working as a single unit. While obviously there are many aspects of science that are readily agreed on, there are also plenty of scientists who are constantly disagreeing, arguing, and pushing their own pet theories. Most of them would love to be the Einstein or Newton of their generation and beyond. Taking down Einstein would be more than just a feather in their career cap. They would become virtual legends.
Now this does not mean Einstein was perfect or that his ideas will last forever. After all, Einstein did not buy into quantum physics because he did not like their lack of order and logic. He also dismissed his own cosmological constant, even though ironically it has turned out to be right. But science and its participants are not in lockstep with each other; it is a continually growing process that is constantly being challenged from within and without. That is what keeps science from turning into just another dogmatic cult.
Ljk, I fear that the ill placement of your interesting comments of Feb 28 may further obfuscate the discussion in hand. I put out a general call for any that knows of any reason that special relativity contradicts neutrinos being tachyons to state it. From this I have only excluded
a) strictly religious objections such as problems with the concept of freewill
b) anything requiring a detailed model of how it relates to quantum mechanics such as Cherenkov radiation.
I realise that there is another type of objection that I shouldn’t have left out, and that is if there is some clear experimental evidence for neutrinos acting as if they were ordinary tardyons under other condition. If so I would love to know about them.
Please believe me when I say that, to me, the greatest mystery is not if neutrinos could be ftl, but that many scientists keep repeating that this contradicts SR without giving a coherent explanation. The first mystery should be answered during my lifetime, but it seems to me as if the second may remain unanswered forever.
PS, great to see you acknowledging that sciences strength is that it is not a “monolithic structure working as a single unit”, but we could go much further down this path and make science more powerful still if we understand the human weakness of wanting to understand everything in terms of coherent stories, such that we cling to paradigms unhealthily tightly.
Cerenkov radiation and neutrinos? You’re joking, right?
@Rob:
Surely you know about the way that FTL contradicts causality. If you show me anything, ANYTHING,that goes faster than light, I will find you a frame of reference where it will be detected before it is created. Such is the curse of space-like trajectories. I believe this is the reason FTL is said to be incompatible with SR, but I am a bit rusty. There may be better ones that I am missing.
Ron S, good point. I off cause meant its weak equivalent, but if you reread point b) note that I only said such as. Actually I don’t even know if the weak analogue of this effect has name.
Not precisely ?erenkov radiation, but there are analogous processes. See this paper and also the discussion on Jacques Distler’s blog (note: that is a blog that requires a browser that supports MathML). Dominant process should be pair Bremsstrahlung resulting in emission of electron/positron pairs, which should result in the energy of the detected neutrinos being independent of the initial energy and inconsistent with the measured energies. So clearly something is missing from the model: either we haven’t actually got superluminal neutrinos after all, or somehow the decays are suppressed, or…?
Rob Henry said on February 28, 2012 at 17:05:
“PS, great to see you acknowledging that sciences strength is that it is not a “monolithic structure working as a single unit”, but we could go much further down this path and make science more powerful still if we understand the human weakness of wanting to understand everything in terms of coherent stories, such that we cling to paradigms unhealthily tightly.”
So how would you have us understand everything? Whose method and/or stories would be acceptable? And are you referring to deep cosmological mysteries of space and time, or much closer and tangible things? As for the latter, things like gravity pulling one object towards another is a fact. As for the former, it may be a long time if ever before humanity figures out such things. In the meantime, ideas and theories will be made. They have more benefits than drawbacks. Most real scientists accept theories as just that, theories.
Personally I think that while it is amazing humanity has come as far as it has in terms of knowledge, science, and technology, we have a very long way to go with many other things, including whether we know alien life exists or not. Quite frankly I think it is going to take bigger and better minds than ours to make the major cosmic discoveries.
The other annoying thing that happens when you allow FTL in special relativity is that the equations start spewing out imaginary numbers for quantities like mass and the rate of passage of time. Needless to say this kind of thing causes a few headaches, even if you subscribe to the “shut up and calculate” interpretation of physical theories.
@Andy, to me imaginary mass never sounded too bad, but imaginary time sounds a fair handful. I will look into that, thanks.
@Eniac, I can see that for all effects directly tied to neutrinos causality must not apply, for example we must equally be able to say that neutrinos are generated in their detectors, and by amazing luck sent back in parallel to their generators. I can see how that is quite some problem, and possibly one that I have underrated.
As far as indirectly tying neutrinos to causality, I believe that is very easily solved by assuming that no observers the have freewill to do that.
Thank you all for the help.
@ljk no stories are acceptable, only the predictive power of models. This exists irrespective of whether the underlying themes that helped build them have any basis in reality or not.
Ljk, you must have wondered what all the excitement over the possibility of TOE was. If it does not really exist we know of nothing other than prediction that was fundamentally true from science. But, oh, what incredible benefits that has gained mankind so far.
Eniac
“If you show me anything, ANYTHING,that goes faster than light, I will find you a frame of reference where it will be detected before it is created. Such is the curse of space-like trajectories. I believe this is the reason FTL is said to be incompatible with SR, but I am a bit rusty.”
This argument can very well be used to support the notion that general relativity is incompatible with special relativity.
General relativity equations (combined with the relativity of simultaneity from special relativity) allow for travel into the past, for example by rotating around a spinning singularity.
And yet, this causes very little oposition to general relativity.
andy, thanks for pointing me at that paper. I had meant to read it when it came out but then completely forgot about it. You gave me the reason I needed to read it. It’s nice and short, but delves into some Lorentz-violation theoretics with which I am unfamiliar. Distler’s coverage adds a bit of background though not much. I find it particularly interesting that, by that theory, a neutrino could be ever so slightly superluminal yet still have a time-like trajectory. Curious.
I had no problem with rendering the MathML in both Firefox and Opera. The latter choice of browser seems totally appropriate under the circumstances! ;-)
“This argument can very well be used to support the notion that general relativity is incompatible with special relativity.”
No. GR is SR extended to account for gravitation.
“General relativity equations (combined with the relativity of simultaneity from special relativity) allow for travel into the past, for example by rotating around a spinning singularity.”
You mean a black hole of a very specific configuration and content. These configurations may be (and likely are) unphysical in our spacetime. The EFE can be applied to, and has solutions for, many spacetimes other than the one we inhabit. This keeps mathematicians entertained.
Eniac, I have just noticed a possible difference between “cause” events and “effect” ones. To my casual inspection, the nature and pattern of entropy and enthalpy changes looks typically different for each. Perhaps then cause and effect can be seen as just a pair of linked events that have the very odd property that, when timelike separated, they inevitably occur in one order due to the nature of our universe.
@Avatar:
Again, I am a bit rusty, but I think here you are confusing closed time-like trajectories with space-like trajectories. The former may be allowed, the latter are not. Only GR allows closed time-like trajectories (if so), but AFAIK the ramifications for causality are not nearly as bad as with space-like trajectories.
Ron S
““General relativity equations (combined with the relativity of simultaneity from special relativity) allow for travel into the past, for example by rotating around a spinning singularity.”
You mean a black hole of a very specific configuration and content. These configurations may be (and likely are) unphysical in our spacetime. The EFE can be applied to, and has solutions for, many spacetimes other than the one we inhabit. This keeps mathematicians entertained.”
I mean a rotating black hole which, as per GR, will form when a rotating body collapses AKA is practically guaranteed to exist in our spacetime.
““This argument can very well be used to support the notion that general relativity is incompatible with special relativity.”
No. GR is SR extended to account for gravitation.”
And?
It changes nothing to the fact that GR’s equations allow for travel into the past AKA as per said argument, GR is incompatible with SR.
The fact that GR is an extension of SR and allows travel into the past supports the ideea that SR does not forbid travel into the past.
Eniac
“Again, I am a bit rusty, but I think here you are confusing closed time-like trajectories with space-like trajectories.”
Not really, Eniac.
A spinning singularity creates a frame-dragging effect (as per GR). From the perspective of someone far outside the singularity, this frame-dragging will make an object (locally moving just beneath the speed of light around the singularity) move at above the speed of light.
And once you have that, you can use SR’s relativity of simultaneity to find systems of reference where said object moves backward through time.
This solution to GR’s equations is known for some time, Eniac. I’m sure you can find a more detailed account on the net.
“I mean a rotating black hole which, as per GR, will form when a rotating body collapses AKA is practically guaranteed to exist in our spacetime.”
A naturally-occurring BH due to stellar collapse does not support time travel of any variety. A typical solution that permits what you describe requires a rotating cylindrical BH. Very unnatural. And then there’s the exotic matter requirement.
“And?”
You need to brush up on relativity physics. There are many textbooks that can help you with this.
Ron S
“A naturally-occurring BH due to stellar collapse does not support time travel of any variety. A typical solution that permits what you describe requires a rotating cylindrical BH. Very unnatural.”
Kerr singularities are naturally occuring – that is, as per GR, they are. And they do support the GR solution I talk about.
5 minutes and you’ll find one of many papers that mentions it:
http://arxiv.org/ftp/arxiv/papers/1008/1008.3244.pdf
Godel discovered the solution in 1949.
And what about exotic matter? Kerr singularities don’t need it.
“You need to brush up on relativity physics. There are many textbooks that can help you with this.”
You don’t impress with your relativity physics knnowledge either, Ron S.
You really should read up some of those textbooks you mention, as opposed to running on blind faith.
Avatar, that is one strange paper. Has this paper been peer reviewed and published anywhere? From a quick search it appears to itself have fallen into a black hole. Maybe that is for the best. Consider:
He requires two rotating black holes in close proximity that will maintain an exact, stable configuration. That would be a neat trick. The dynamics of their mutual movement is ignored, yet they cannot stand still and will indeed quickly merge and destroy whatever crazy conditions he claims, including the removal of the need for negative mass to maintain this purported stable condition.
If that isn’t enough, he proposes capturing micro-black holes that the LHC might produce and thence go on to arrange them thusly and poke them with negative charges. This is to not only prove his hypothesis (?), but also the Everett many-worlds interpretation of quantum theory. If nothing else he has ambition.
Moving on…my point re brushing up on relativity physics was your persistent misunderstanding of the relationship between SR and GR. This is basic stuff that you ought to know. But here is my point in brief. When you take the limit of the EFE toward zero spacetime curvature they reduce to SR, exactly. The curvature is, of course, gravitation.
http://www.technologyreview.com/blog/arxiv/27319/
Update: Black Holes, Safety, and the LHC Upgrade
Some additional comments on why safety should be a central part of any plans for an upgrade to the LHC
kfc 11/09/2011
Update 9 November
In response to some of the comments below, let me explain one of the concerns over the standard assurances given by particle physicists about the safety of the LHC.
Their argument is that the planet Earth has been bombarded by high energy cosmic rays for billions of years. These particles would have collided with particles in our atmosphere at much higher energies than are possible at the LHC. So if a catastrophe were possible, it would have happened by now. That means the continued existence of Earth, and indeed many other astronomical bodies, is powerful evidence that the LHC is safe.
The problem is this: There is an important difference between the collisions that occur in the atmosphere and those that occur at the LHC.
Cosmic rays hit the atmosphere at a substantial fraction of the speed of light. That means the debris from these collisions also travels at a substantial fraction of the speed of light, giving it limited time to interact with the Earth.
The collisions at the LHC are different. These involve two beams, both travelling at almost the speed of light but colliding head on. So the collision occurs at rest with respect to the Earth.
That’s a significant point. It means that the debris from the collision can hang around for longer and so have a greater chance of interacting with Earth.
When this effect is taken into account, it is not at all clear that similar events have taken place regularly in our atmosphere or indeed anywhere else.
That doesn’t prove the LHC is dangerous, far from it. But it does show that the standard safety assurance is not as water tight as particle physicists would have us believe. If there are any doubts over this assurance, they must be addressed.
CERN has not addressed this concern or any of the others that have emerged since it published its original safety report. That’s not really surprising: it has an obvious vested interest in the LHC.
But this situation cannot continue. That’s why the safety of the LHC needs to be reviewed by an independent group of scientists with a background in risk analysis but no professional or financial connections with CERN.
The proposed upgrade to the LHC provides the perfect opportunity
___________________________________
Original post
It’s been 10 years now since physicists first raised the possibility that particle accelerators on Earth could produce microscopic black holes. This phenomenon initially seemed hugely exciting since it hinted at a way scientists could test their ideas about quantum gravity, the theory that reconciles quantum mechanics with general relativity.
Since then, much of the excitement has died down. It turns out that the energy required to create these objects vastly exceeds what is possible in the world’s most powerful accelerators and, indeed, is far more than found in the most powerful cosmic ray ever recorded.
There are various loopholes that allow micro-black holes to form at lower energies, however. The most widely discussed is the possibility that the universe has extra dimensions on microscopic scales that significantly weaken gravity at this level. These dimensions would need to operate at a scale greater than 10^-19 metres to allow microscopic black holes to form more easily.
But here again, the evidence is constraining this idea. The world’s most powerful accelerator, the Large Hadron Collider, has been running for a year or so and so far failed to produce black holes with masses up to 4.5 TeV. That means any extra dimensions must be smaller than 10^-12 metres in size.
Nevertheless, black holes could still be produced at the LHC at a rate of perhaps 100 per year. But how to spot them?
Today, Marcus Bleicher at the Frankfurt Institute for Advanced Studies in Germany and a few pals outline some of the open problems concerning black hole production and detection at the LHC, assuming it takes place at all.
These guys assume that after microscopic black holes form, they would go through four phases. First there is the balding phase in which the newly formed back hole evolves from a highly asymmetric object to a more symmetric one, shedding its asymmetry through gravitational radiation.
In the second phase, called the spin-down phase, the black hole loses mass and angular momentum by emitting Hawking radiation. The third, the Schwarzschild phase, the black hole becomes spherical and the rate of mass loss slows down. And in the final Planck phase, the black hole winks out of existence.
Of these phases, only the Schwarzschild phase in is understood in any detail mainly because of the symmetry involved. The other phases are poorly understood, particularly the Planck phase which can only be described in terms of quantum gravity, which is itself an untested idea.
One thing that could help clarify many of these questions is more data and the possibility of an upgrade to the LHC at some point in the future.
The 800 pound gorilla in all this is the safety of these kinds of experiments. There is a widespread belief in the particle physics community that black hole production is a zero risk procedure. Indeed, particle physicists brook no discussion on this topic and Bleicher and co do not mention it.
By contrast, they point out that the physics involved is highly speculative. Indeed what interests them is the possibility that these processes will reveal new physics beyond our existing understanding of the universe. That’s hard to reconcile with the categorical assurances that the public has been given over safety.
There’s little confidence to be gained from safety assessments that have been carried out in the past.. Back in the late 90s, a reader’s letter in Scientific American raised the question of whether the Relativistic Heavy Ion Collider (RHIC) then being built at the Brookhaven National Laboratory, could produce black holes that might destroy the planet.
As a result, Brookhaven’s director commissioned a report from four physicists on the safety of the machine. This report concluded that the probability of catastrophe was 2 x 10^-4, describing this as “a comfortable margin of error”. Another report by a group of CERN physicists came to the “”extremely conservative conclusion [that] it is safe to run RHIC for 500 million years.”
These papers were widely used at the time to provide reassurance to the public and yet both later turned out to contain serious errors. The “comfortable margin of error” is actually a 1 in 5000 chance–not one that most people would consider comfortable. When this was pointed out, the team revised its figures by adding another zero onto the number making it a 1 in 50,000 chance, adding that “we do not attempt to decide what is an acceptable upper limit on [the probability of a disaster].”
The CERN group had mangled its numbers too. It turned out that their calculations merely suggested that there was a low probability that Earth would be destroyed very early on in a run at RHIC. In fact, their calculations were consistent with a high probability of planetary destruction over a long run.
None of these errors were widely reported.
Just before the LHC was due to be switched on, CERN commissioned its own report on the safety of what is now the world’s most powerful accelerator. This report concluded that the machine was safe.
An important question is what confidence the public should place in this report. There are various reasons to be cautious, not least of which are the errors that appeared in earlier assessments.
Just as serious is the fact that the report was written by five employees at CERN who relied on the scientific work of one other CERN employee and a scientist with a pending visiting position at the organisation.
These are people whose entire careers and livelihoods depended on the LHC being switched on. With the best will in the world, it’s hard to see how this was a sensible choice.
Since then the debate has moved on, with a number of new concerns being raised over safety. We’ve covered this in this blog on several occasions. These concerns have yet to be addressed.
What’s needed, of course, is for the safety of the LHC to be investigated by an independent team of scientists with a strong background in risk analysis but with no professional or financial links to CERN. A competent team could surely be put together even though this condition would probably exclude most particle physicists.
The talk now is of an LHC upgrade to increase the machine’s luminosity and its energy to some 16.5 TeV. Safety should be a central part of these plans and yet it is not. The public should demand to know why.
Ref: http://arxiv.org/abs/1111.0657: Micro Black Holes In The Laboratory
@Avatar:
As far as I recall, a time like trajectory is time-like in all frames of reference, in SR as well as in GR. What you are saying contradicts this. Most likely there is a misunderstanding involved. If it is mine, than there exist trajectories that are time-like from one reference frame and space-like from another. Are you ready to claim this, really?