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Intergalactic Race Shows That Einstein Still Rules

samzenpus posted more than 4 years ago | from the the-speed-of-right dept.

Space 227

Ponca City, We love you writes "The NY Times reports that after a journey of 7.3 billion light-years, a race between gamma rays ranging from 31 billion electron volts to 10,000 electron volts, a factor of more than a million, in a burst from an exploding star, have arrived within nine-tenths of a second of each other. A detector on NASA’s Fermi Gamma-Ray Space Telescope confirmed Einstein’s proclamation in his 1905 theory of relativity that the speed of light is constant and independent of its color, energy, direction or how you yourself are moving. Some theorists had suggested that space on very small scales has a granular structure that would speed some light waves faster than others — in short, that relativity could break down on the smallest scales. Until now such quantum gravity theories have been untestable because ordinarily you would have to see details as small as the so-called Planck length, which is vastly smaller than an atom — to test these theories in order to discern the bumpiness of space."

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i'm confused (2, Insightful)

circletimessquare (444983) | more than 4 years ago | (#29912023)

they arrived within 9/10th of a second of each other

which indicates the opposite of the story's summary

Re:i'm confused (1)

selven (1556643) | more than 4 years ago | (#29912107)

Probably gravitational lensing making some of the gamma rays more curved than the others. Or whatever event caused them is not instantaneous (like every other large-scale event in existence).

Re:i'm confused (2, Insightful)

schnikies79 (788746) | more than 4 years ago | (#29912155)

If it wasn't instantaneous, or nearly, how can we even use this data? They could have been released minutes or more apart.

How do they know (4, Insightful)

2.7182 (819680) | more than 4 years ago | (#29912179)

that the photons all left at the same time?

Re:How do they know (5, Informative)

John Hasler (414242) | more than 4 years ago | (#29912429)

The event was approximately 2.2 seconds long. Thus it is plausible that these two photons left .9 seconds apart.

Re:How do they know (4, Interesting)

Richard_at_work (517087) | more than 4 years ago | (#29912519)

Its also plausable that they left at the same time, and arrived 0.9 seconds apart. How do we tell though?

Re:How do they know (4, Informative)

John Hasler (414242) | more than 4 years ago | (#29912531)

We don't, and it doesn't matter. .9 seconds is much smaller than would be predicted by the theories in question.

Re:How do they know (1)

Richard_at_work (517087) | more than 4 years ago | (#29912649)

I think it is pretty much the only thing that matters - until you can say when the photons left in relation to each other, there is no way you can say the delay validates or invalidates any of the theories in question.

Re:How do they know (5, Insightful)

jabuzz (182671) | more than 4 years ago | (#29912763)

Not true, if the theory requires that they would be separated by say 900 seconds, they left within 2.2 seconds of one another maximum, and we observe them at 0.9 seconds apart, then the theory is proved wrong.

Re:How do they know (4, Funny)

selven (1556643) | more than 4 years ago | (#29913259)

So God runs the universe using Verizon technologies?

Re:How do they know (5, Interesting)

gnick (1211984) | more than 4 years ago | (#29912785)

Not true. If we know that the event that generated the rays lasted only 2.2 seconds and we have a theory that would delay one of the rays by more than 3.1 seconds (2.2 + 0.9) relative to the other, we can invalidate that theory. From my understanding, that is exactly the case we're dealing with. You are correct though that this cannot completely validate any specific theory - All it can do is reinforce the assumption that our current theory is more accurate than some others proposed and eliminate some competing ideas.

Re:How do they know (1)

LordLimecat (1103839) | more than 4 years ago | (#29913445)

Your post makes sense except that "more accurate" implies that "proved wrong tomorrow" is somehow better than "proved wrong today". Either its right, and will never be proved wrong, or it is wrong, and may eventually be proved as such.

Re:How do they know (1)

Dare nMc (468959) | more than 4 years ago | (#29913481)

Makes me wonder how, and how long they were looking for this. It seams like a whole stream of photons could have bounced off a celestrial body 2000 light years away, and the faster light stream came past earth 2000 years ago as well (and the slower stream will reflect from the same source, and come by us in 2000 years.) If they were just looking for a stream of photons within 1 second of each other, eventually we were likely to find proof, even if Einsteins theory was wrong.

Re:How do they know (1)

2.7182 (819680) | more than 4 years ago | (#29912733)

But how do we know the length of such an event so accurately? Maybe it took 10 minutes.

Re:How do they know (2, Interesting)

Anonymous Coward | more than 4 years ago | (#29913423)

Because it is incredibly unlikely that:
1) the event lasted 10 minutes
2) produced gamma rays steadily decreasing in energy
3) such that the effects of the difference of the speed of light on the particles over 7.3 billion years would compress the burst to 2.2 seconds
4) that we would be located at the exact location to observe a burst of only 2.2 seconds (closer or farther away and the burst would still be spread out)

Since all gamma ray bursts are short and have different energy radiation, there are only two possibilities. Either space time is not bumpy at plank distance, therefor the speed of light is not dependant on wavelength, or we are magically located at the perfect distance from gamma ray burst events that they all compress to such a short time, requiring divine providence to explain the happenstance.

Re:How do they know (1)

LordLimecat (1103839) | more than 4 years ago | (#29913573)

Wouldnt the theories be wrong, just on a different scale than predicted, if the more energetic signals had different travel times?

Re:How do they know (1)

sexconker (1179573) | more than 4 years ago | (#29912637)

Its also plausible that they left 2.2 seconds apart, and arrived 0.9 seconds apart in the opposite order. How do we tell though?

Re:How do they know (3, Informative)

KillerBob (217953) | more than 4 years ago | (#29913323)

We're talking about a distance of 7.3 billion light years. Even if the expected difference in speed is 1m/s (absolutely miniscule difference against the speed of light), we're talking a difference significantly greater than 3.1s in travel time.

Re:How do they know (3, Insightful)

csartanis (863147) | more than 4 years ago | (#29913071)

Perhaps your theory is _not_ plausible, and the scientists know more than the average slashdot commenter?

No one knows more than the average slashdotter (1)

John Hasler (414242) | more than 4 years ago | (#29913139)

Of course, most of what he knows isn't true...

Re:How do they know (1)

noundi (1044080) | more than 4 years ago | (#29912607)

The event was approximately 2.2 seconds long. Thus it is plausible that these two photons left .9 seconds apart.

Mod parent up, obviously this is a mere effect of the size of this sun. Different layers of the sun produced different wavelenghts in the bursts as the sun would consist of various elements in layers, but you already knew this.

Re:How do they know (3, Funny)

Tiger4 (840741) | more than 4 years ago | (#29912777)

Do we call in the MythBusters to stage an experiment? I need to see a Confirmed, Plausible, or Busted branding iron before I believe anything.

Re:How do they know (1)

publiclurker (952615) | more than 4 years ago | (#29913025)

Jamie wants BIG boom!!

Re:How do they know (1)

mikael (484) | more than 4 years ago | (#29913203)

What if there was only one super-high-energy photon that left the supernova, and collided with an proton creating two gamma rays later on?

Re:How do they know (0)

Anonymous Coward | more than 4 years ago | (#29913527)

That case in highly improbable as conservation of momentum requires the two photons to be produced in opposite directions.

Re:How do they know (1)

LordLimecat (1103839) | more than 4 years ago | (#29913537)

How can they know the length of the event? The particles were RECEIVED over a space of 2.2 seconds. The issue is that the only information we have (that i could see in the article) is based on EMS signals, and that any inferences we draw from that data will RELY on our theories on how EMS signals move and behave. If Einstein is completely wrong, and if gravity works in vastly different ways at larger scales, we have no way of validating or refuting any of those based on THIS data. What if the higher energy signals were released much later, but traveled faster, so that it appeared to be a 2.2 second event?

Re:How do they know (1, Funny)

pilgrim23 (716938) | more than 4 years ago | (#29912543)

they didn't. the slower one was waiting for its wife to get ready.

Obligatory analogy (0)

BForrester (946915) | more than 4 years ago | (#29912915)

The summary *is* a bit skimpy on important details.

A - My brother and my parents, travelling in separate vehicles, arrived at my house at the same time.
B - Therefore, my brother's Ferrari and my parents' RV both travel at the same speed.

No logical gaps between A & B there. Move along.

Re:Obligatory analogy (1, Insightful)

Anonymous Coward | more than 4 years ago | (#29913255)

Better analogy (RTFA)

A - My brother and my parents left the same destination within 2 seconds of each other
B - They traveled along the same path without stopping to my house in different vehicles
C - They arrived at the same time
D - therefore they traveled at the same speed

Re:Obligatory analogy (1, Funny)

Anonymous Coward | more than 4 years ago | (#29913307)

Are they driving the same route? Did your brother not ride with so he could burn down a j? Will he share?!?

Re:Obligatory analogy (1)

MillionthMonkey (240664) | more than 4 years ago | (#29913371)

Didn't they stop at a diner along the way?

Re:i'm confused (1)

John Hasler (414242) | more than 4 years ago | (#29912469)

> Probably gravitational lensing making some of the gamma rays more curved than
> the others.

No. Gravity has exactly the same effect on all photons. However, the photons were emitted over a period of several seconds.

Re:i'm confused (0, Redundant)

DreadPiratePizz (803402) | more than 4 years ago | (#29912123)

Over 7.8 billion light years, a difference of 9/10 of a second is such an incredibly small margin.

Re:i'm confused (3, Funny)

MightyMartian (840721) | more than 4 years ago | (#29912631)

It's not the distance, it's very likely that the different photons were emitted at slightly different periods during the burst. It would be like two cars leaving a parking lot, one after the other, and both traveling at the same speed. Obviously the one behind the other will never overtake it.

Re:i'm confused (4, Informative)

Nevynxxx (932175) | more than 4 years ago | (#29912137)

I'm guessing that the error bounds on the readings were great enough that 0.9 seconds over 7.3billion years, was within them....

Re:i'm confused (4, Funny)

oodaloop (1229816) | more than 4 years ago | (#29912149)

Probably due to the reflex time when they started and stopped their stopwatches.

Re:i'm confused (5, Informative)

eldavojohn (898314) | more than 4 years ago | (#29912185)

The importance is that that puts the effect at smaller than a planck length (which is the assumed smallest possible distance that something measurable can happen in classical physics). From the first article:

The spread in travel time of 0.9 second between the highest- and lowest-energy gamma rays, if attributed to quantum effects rather than the dynamics of the explosion itself, suggested that any quantum effects in which the slowing of light is proportional to its energy do not show up until you get down to sizes about eight-tenths of the Planck length, according to the Nature paper, whose lead author was Sylvain Guiriec of the University of Alabama.

Granted they say it would have to be proven much smaller than a planck length for most people to accept this as empirical proof, it is empirical data backing Einstein. The 9/10s could be due to the explosion or a physical effect but the latter is now more unlikely given the many light year distance.

Re:i'm confused (4, Funny)

Tiger4 (840741) | more than 4 years ago | (#29912877)

You read the article. Obviously, injecting evidence and facts into the discussion is not helpful with the wild speculation, conjecture and skepticism of the uninformed.

Re:i'm confused (4, Funny)

Anonymous Coward | more than 4 years ago | (#29912247)

The light propagated through space for 7.3 billion years. A delta of +/-0.000000000000000039% is not even close to statistically significant. It could have been from local variations in the density of a nebula or something.

Re:i'm confused (1, Interesting)

Anonymous Coward | more than 4 years ago | (#29913029)

So...just to be difficult...is it worth pointing out that the measurement of the distance is dependent upon an assumption of the constancy of the speed of light? FWIW, I fully believe the laws of physics haven't "changed" over the course of the history of the universe, but if you're trying to argue with someone who believes that the speed of light isn't constant, I'm not certain how this helps. Of course, for people who actually are interested in real science, it's a useful and important result, but it doesn't seem likely to convince a disbeliever

Re:i'm confused (5, Informative)

FlyingBishop (1293238) | more than 4 years ago | (#29913283)

It doesn't prove that the speed of light is constant, but it does reasonably prove that the speed of light is independent of wavelength, since they left from the same source at the same time.

Re:i'm confused (5, Insightful)

zerosomething (1353609) | more than 4 years ago | (#29912279)

9/10th of a second is only about 3/4th the distance from earth to the moon. I don't know for sure but I think that's a rather small difference and could be accounted for just by the size of the star that exploded. Our own sun is about 4 seconds across isn't it?

Re:i'm confused (5, Funny)

Anonymous Coward | more than 4 years ago | (#29912689)

9/10th of a second is only about 3/4th the distance from earth to the moon. I don't know for sure but I think that's a rather small difference and could be accounted for just by the size of the star that exploded. Our own sun is about 4 seconds across isn't it?

The speed of light = 299 792 458 m / s (commonly 3.0 * 10^8 m/s)
The average centre-to-centre distance from the Earth to the Moon is 384,403 kilometres
(384 403 kilometers) / the speed of light = 1.28223039 seconds

The diameter of the sun = 1391000 kilometers
(1392000 kilometers) / the speed of light = 4.64321221 seconds

Either you do good math in your head, or I respect your physics teacher for teaching you such interesting facts.

Re:i'm confused (2, Funny)

arun84h (1454607) | more than 4 years ago | (#29912867)

His in-head rounding skills, however, were taught by Lorena Bobbitt.

Re:i'm confused (4, Funny)

Anonymous Coward | more than 4 years ago | (#29913407)

"When you have a period, chop it off?"

Re:i'm confused (1)

AndrewNeo (979708) | more than 4 years ago | (#29913073)

4.64 seconds [wolframalpha.com]

Re:i'm confused (5, Insightful)

radtea (464814) | more than 4 years ago | (#29913425)

I don't know for sure but I think that's a rather small difference and could be accounted for just by the size of the star that exploded.

You're confused because the summary, and the press release on which it is based, are misleading and wrong.

This is a gamma ray burst (GRB), which originate from neutron stars, not a super-nova (which is the only reasonable meaning one can give "exploding star".) Neutron stars are small, resulting in much finer burst timescales.

The paper discusses the time-structure of GRB's, which has been extensively studied. The fundamental result they get is from a single high-energy gamma ray at the end of the last spike in the burst, which comes 0.9 s after the onset of that spike (seen in the lower-energy photon flux). They do a lot of analysis to argue that the most plausible explanation of that single photon is that it is a member of that spike rather than a random cosmic ray. Anyone familiar with modern statistical techniques will see that this is straightforward, albeit non-trivial.

This is the way science works: we squeeze limited and imperfect experimental evidence as hard as we can using established theory and other, supporting, observations. All the "yeah, well, it could be something else" kind of commentary we see so much of on /. is irrelevant to the scientific process, because it is doing nothing but repeating what everyone already knows: sometimes the most plausible explanation turns out to be wrong.

The exciting thing about this measurement is that they have shown it is possible to put quantum gravity to a rather good test using entirely conventional gamma-ray spectroscopy techniques, and repeating this kind of measurement over the next few years or decades on different bursts will rapidly push down the limits on potential planck-scale effects, because eventually we'll see bursts where there are a few high-energy photons closer to the onset, or we will see bursts from objects at larger (known) distances.

The present authors argue, rightly, that their observation makes theories that have a linear dependence of light velocity on wavelength less plausible. At some point in the next few years it is likely that those theories will be dead, and there's really nothing so beautiful as a theory killed by a fact.

Re:i'm confused (1, Insightful)

hotair (600117) | more than 4 years ago | (#29912477)

That was my thought exactly. Then it occurred to me that an exploding star might actually have diverse points of origin as far apart as 0.9 light-seconds. If 7.3 billion light-years of travel is insufficient to create greater divergence than 0.9 seconds, we may have to wait for a much more distant event. My guess is that they decided that the noise of diverse points of origin sufficiently overrides the question of 0.9 seconds to the point that absent other evidence, it confirms rather than invalidates the theory of relativity.

Re:i'm confused (5, Insightful)

natehoy (1608657) | more than 4 years ago | (#29912527)

Actually, it really indicates nothing, except that any "bumpiness" of space doesn't have a profound effect on the speed of light within the wavelength range tested. It's good data. However, this neither proves nor disprove there was an effect, just proves that the effect (if it exists) is very insignificant at the tested wavelengths.

Insignificant != Nonexistent
Tested Wavelengths != All Wavelengths

In order to prove or disprove the theory that light changes speed based on wavelength or other factors, you'd need to be sure that both pulses started the race at the exact same moment, that the two pulses travel through the same space without interfering with each other,and that they complete the race at the exact same moment (ie, within the margin of error of your testing equipment). The margin was almost one second, which is terribly insignificant when compared to 7 billion years, of course, but demonstrates clearly one of the following three things:

1. The pulses left about a second from each other, which we can neither prove nor disprove.
2. The test equipment was flawed and they really did arrive at the exact same time (which leads to #1, maybe they left at different times and just happened to arrive at the exact same moment).
3. The speed of the various wavelengths WAS affected by "space potholes", but it took 7 billion years to accumulate less than one second of variance.

If #3 is possible, which it still is even after this test, then the theory of bumpiness of space has not been disproven, it just appears that evidence points toward the bumps being really, really small or somehow only marginally effective at affecting the speed of light.

Plus, the original article goes on to explain that the tested wavelengths were relatively large, and that much smaller wavelengths might be more susceptible to the "bumpiness" of space depending on the size of the bumps. If the bumps are really tiny, then they might have just tested wavelengths that were too large to be affected by them. If we can measure some really high-frequency (low-wavelength) pulses against the ones we think are nearly identical, that would be much more compelling data.

Re:i'm confused (1)

JamesP (688957) | more than 4 years ago | (#29912685)

You sir, are a true scientist.

I'm really tired of "skeptics" that in reality don't want to see anything.

A true skeptic would not suddenly ignore every other event where there has been a different in arrival times (similar to these), with some lame excuse. But that's exactly how TFA sounds.

Re:i'm confused (4, Interesting)

Rary (566291) | more than 4 years ago | (#29913299)

We know that the pulses were caused by an event that lasted 2.2 seconds, therefore we know that they left anywhere from 0 to 2.2 seconds apart. However, the point isn't to determine a simple boolean result to the question "did they arrive at the same time", the point is to invalidate the predictions of theories. The existing theories predicted that the arrival times of these pulses, having left at most 2.2 seconds apart, would be at a minimum significantly more than 0.9 seconds. However, they were not, therefore the theories' predictions are wrong, and thus the theories are invalid. The one theory that predicted that they would arrive at most 2.2 seconds apart remains — not proven, but still not disproven. That's how science works.

string theory (3, Funny)

astar (203020) | more than 4 years ago | (#29913411)

Yah, but think of the poor string theorists. Here they spend 30 years working on it, and they stack the department hiring processes so they will not be criticized for never have created a testable conjecture. Now some data comes in and half their theories crash.

Re:i'm confused (1)

sdguero (1112795) | more than 4 years ago | (#29912547)

Yes but that small of a difference (9/10th of a sec) across a a spectrum covering millions of magnitudes across almost 8 billion light years of space and time means the change is occurring at levels less than the plank constant, i.e. it confirms Einstiens traditional understanding which doesn't worry about the chop at lower levels (since the change is soooo small), AND it pushes our grasp of the under pinnings of the universe a little further along (by confirming and helping refine other quantum theory measurements). Anyway, I thought TFA was cool... :)

Re:i'm confused (1)

JamesP (688957) | more than 4 years ago | (#29912723)

Thank you!

Not to mention other events where this effect has been much more exaggerated.

Re:i'm confused (1)

mhaskell (658865) | more than 4 years ago | (#29912971)

Possibly female photons? Their line was longer to get out of the star.

I was thinking the same thing (0, Troll)

WheelDweller (108946) | more than 4 years ago | (#29913303)

And think this through with me:

Lights/electrons/etc left 7.3 billion years ago. The starter whistle began LONG before man, while the planet was still 'molten lava'.

How did they know the flow was coming? Is this more junk science like GlobalWarming(TM)?

Re:i'm confused (1)

Geoffrey.landis (926948) | more than 4 years ago | (#29913461)

they arrived within 9/10th of a second of each other

which indicates the opposite of the story's summary

Notice the key word here, "within".

One second in 9.3 billion years is a pretty good measurement. It indicates a difference in speed of no more than 0.0000000000000003 percent.

Slow news day. (-1, Flamebait)

Afforess (1310263) | more than 4 years ago | (#29912039)

Do we really, we need an article that says:

"Status Quo: Unchanged."

Really? Incredible.

In other news, water was proven to be wet.

Re:Slow news day. (0)

Anonymous Coward | more than 4 years ago | (#29912145)

well if we lived in a time when water was only theoretically wet i guess that would be big news.

Re:Slow news day. (1, Insightful)

VShael (62735) | more than 4 years ago | (#29912183)

That would be big news, if some smart people had put forward the idea that water, at the molecular level, isn't wet.

(Which it isn't, by the way.)

Re:Slow news day. (1)

tekrat (242117) | more than 4 years ago | (#29913069)

Particle man, Particle man,
Doin' the things a particle can.
What it's like, it's not important, Particle man.
Is he a dot, or is he a speck?
When he's underwater, does he get wet?
Or does the water get him instead?
Nobody knows. Particle man.

Re:Slow news day. (0)

Anonymous Coward | more than 4 years ago | (#29912231)

Do we really, we need an article that says

SCIENCE [xkcd.com] , bitch.

Re:Slow news day. (1)

selven (1556643) | more than 4 years ago | (#29912293)

So an article about the four color theorem being proved is irrelevant because we were already 99.999% certain before it happened?

Re:Slow news day. (5, Insightful)

Tibia1 (1615959) | more than 4 years ago | (#29912327)

What a time we live in where a "slow new day" consists of a 7.8 million year race being recorded (regardless of the results), a fusion reactor is being developed, and a real time speech translator was released.

Re:Slow news day. (2, Insightful)

Anonymous Coward | more than 4 years ago | (#29912487)

Some people just like to get offended. It validates their existence.

Re:Slow news day. (1)

AP31R0N (723649) | more than 4 years ago | (#29913075)

Worse yet, they changed the outcome of the race by measuring it.

i lost 300 big boys on that!

Re:Slow news day. (1)

johno.ie (102073) | more than 4 years ago | (#29913447)

Your point is well made, but it was 7.8 billion years.

Re:Sour Grapes (-1, Offtopic)

conureman (748753) | more than 4 years ago | (#29912575)

I, for one, am glad to hear it; And I don't resent the fact that I wasn't credited for my work.

Re:Slow news day. (0)

Anonymous Coward | more than 4 years ago | (#29912655)

The summary was poor, but so was the article. This should have been more an article about quantum gravity and how one of the theories is potentially wrong and how there are more tests coming.

One interesting thing that stood out is they used the assumption that the effect of quantum gravity would be proportional to the energy of the light; is this what the theories suggested or is this another case of science getting lost in the translation to newspapers?

How do we know (0, Redundant)

Darth Sdlavrot (1614139) | more than 4 years ago | (#29912159)

They didn't leave 9/10ths of a second apart?

Re:How do we know (1)

John Hasler (414242) | more than 4 years ago | (#29912511)

Who said they didn't? The point is that even if they left at the same instant from the same point .9 seconds is much smaller than predicted by the theory in question.

Re:How do we know (1)

CrimsonAvenger (580665) | more than 4 years ago | (#29912709)

Who said they didn't? The point is that even if they left at the same instant from the same point .9 seconds is much smaller than predicted by the theory in question.

No, TFA seems to say that it's slightly smaller than the theory would predict with the 0.9s difference.

But what if the photons that arrived first had left last? That might put the difference in travel time as high as 3.1s....

Re:How do we know (1)

scheme (19778) | more than 4 years ago | (#29913401)

But what if the photons that arrived first had left last? That might put the difference in travel time as high as 3.1s....

I think the scientists writing the paper and the reviewers already considered that possibility. The paper sets bounds on how big of an effect energy / speed interactions could be for photons so they probably used worst case situations to establish the upper or lower bounds as needed.

Re:How do we know (0)

natehoy (1608657) | more than 4 years ago | (#29912809)

We don't. But if we can theorize they left 9/10ths of a second apart, we can theorize they left 150 million years apart and that "space potholes" DID affect their speed to a fairly significant extent.

In other words, this data appears to indicate that any effect would be very small, but if we accept that they left at the exact same time we have a difference that must be explained. And that explanation could be evidence supporting what the article says the test provides evidence against (that the pulses left at the same time and had a variance in their arrival times, therefore their speed was affected by some factor).

And if we assume they left at different times to account for their varying arrival times, we're saying the conditions of the initial phase of the test test are unknown (which is, by the way, very true) therefore it's hard to draw any solid conclusions from the test results.

There could be a way to validate this result. Test different distances. If you test a star at, say, 15.6 billion light years away and get a 1.8 second difference, and a star 3.9 billion light years away and get a 0.45 second variance, then you can reasonably conclude that there IS an effect on speed, and it shows that space may well be bumpy, just not VERY bumpy. If you test stars at various differences and observe a constant 0.9 second variance, then you can reasonably conclude that there is no difference in speed and that some factor is releasing certain wavelengths at different times during the event, and space is looking pretty silky smooth.

Re:How do we know (1)

natehoy (1608657) | more than 4 years ago | (#29912863)

For the pedantics among you (myself included), please replace "15.6" with "14.6" and "3.9" with "3.65". Somehow I got "7.8 billion" stuck in my head instead of the stated "7.3 billion". Stupid brain!

Aliens certify Einstein? (1)

DustCollector (903185) | more than 4 years ago | (#29912181)

Did anyone else read this headline about an intergalactic people verifying Einstein's theories?

Re:Aliens certify Einstein? (0)

Anonymous Coward | more than 4 years ago | (#29912843)

NO, it's about aliens invalidating Einstein's sanity...FROM BILLIONS OF YEARS IN THE PAST

Re:Aliens certify Einstein? (1)

natehoy (1608657) | more than 4 years ago | (#29913149)

[required slashdot meme]

I, for one, welcome our Einstein-validating overlords.

how do we know (3, Insightful)

Anonymous Coward | more than 4 years ago | (#29912187)

that these rays are all from a star which exploded 7.3 billion light years away? what was monitored to predict arrival?

And in related news... (0, Offtopic)

e9th (652576) | more than 4 years ago | (#29912313)

Einstein is no. 9 on Forbes magazine's list of top-earning dead celebrities [forbes.com] , nestled between Dr. Seuss and Michael Crichton.

Maxwell, not Einstein (0)

Anonymous Coward | more than 4 years ago | (#29912485)

Should this give props to Maxwell, rather than (or in addition to) Einstein?

Re:Maxwell, not Einstein (1)

conureman (748753) | more than 4 years ago | (#29912681)

Most people think J.C. Maxwell helped Ringo with percussion on "Abbey Road". Einstein has Box Office Mojo.

Obligatory Maxwell (0, Offtopic)

sexconker (1179573) | more than 4 years ago | (#29912765)

No - Einstein never killed a bitch.

Joan was quizzical - studied pataphycial science in the home. Late nights all alone with a test tube, oh, oh oh, oh.

Maxwell Edison (majoring in medicine) calls her on the phone.

"Can I take you out to the pictures, Jo-o-o-oan?"

But as she's getting ready to go, a knock comes on the door.

Bang bang Maxwell's silver hammer came down upon her head.

Bang bang Maxwell's silver hammer made sure that she was dead.

So-Called? (2, Interesting)

Afforess (1310263) | more than 4 years ago | (#29912651)

I'm curious, why is the Plank-length "So-called"? Hasn't it been firmly established as a unit of measurement?

Re:So-Called? (1)

Compholio (770966) | more than 4 years ago | (#29912955)

I'm curious, why is the Plank-length "So-called"? Hasn't it been firmly established as a unit of measurement?

It's a unit of measurement derived from dimensional analysis. Some believe that the Planck length is the unit that describes the quantization of space, but this assertion has not successfully been tested.

Re:So-Called? (1)

JasterBobaMereel (1102861) | more than 4 years ago | (#29913003)

...It's so small they we don't have anything that can even come close to measuring anything even close to this length, so anything said about conditions at this length is untested (and possibly untestable?), and what we have that explains what happens at these distances (mostly quantum gravity) are highly speculative and many of the hypotheses are contradictory ...

This is an actual case of science being "only an hypothesis" that actually equates to the reporters "Only a theory" ..But this experiment probably discounts at least a few of the flavours of quantum gravity that have been proposed

A decade long project (4, Informative)

mbone (558574) | more than 4 years ago | (#29912677)

This was proposed by G. Amelino-Camelia et al. back in 1998 [nature.com] ; here [arxiv.org] is a review from 2004. Even though the wavelengths of even the most energetic gamma rays are much, much, longer than the Planck length, roughness in space time at the Planck length adds up over cosmological distances, and could be in principle detectable. (The Planck length can be thought of heuristically as the length at which the gravitational effects of virtual particles should be strong enough to create virtual black holes; general relativity cannot be ignored in quantum mechanics at that scale, and vice versa.) What this current test is ruling out is a particular violation of Lorentz invariance - a variation of photon speed with energy. There were similarly negative results using radiation from the Crab nebula in 2003 [nature.com] .

It should be noted that this does not rule out quantum gravity - it seems pretty clear that General Relativity and Quantum Mechanics cannot both apply at the Planck scale. What this work is doing is beginning to constrain models of quantum gravity (there is as yet no general theory that makes precise predictions). What would be really cool is to detect some effects, which would maybe help nudge the theorists along.

Monster Strikes Again (4, Funny)

sexconker (1179573) | more than 4 years ago | (#29912691)

So the $500 high-energy gamma-output cables I bought actually DON'T improve my ping?

FUCK YOU MONSTER CABLE!

Planck length (4, Funny)

PinkyDead (862370) | more than 4 years ago | (#29912697)

Aaarrggghh!!!

Einstein still being proved correct (1)

defyg3 (413049) | more than 4 years ago | (#29912743)

I'm seriously blown away by how great of a scientist this guy was. I mean, its 100 years later and he is STILL being proved correct. Imagine what we could do if we still had this guy around. Its just so amazing to me.

Re:Einstein still being proved correct (0, Offtopic)

im_thatoneguy (819432) | more than 4 years ago | (#29913271)

Decades ago I observed that the sky was blue. People to this day people still find evidence I was correct as a child. I imagine in 1,000 years people will still be recognizing the correctness of my observations. I am like a God among men!

Enough is enough (2, Funny)

oldhack (1037484) | more than 4 years ago | (#29912933)

This Einstein guy is starting to really piss me off. Someone gotta take him down a notch or two.

Obligatory (0)

ub3r n3u7r4l1st (1388939) | more than 4 years ago | (#29913215)

I, for one, welcome our new race of Einsteinian intergalactic overlords!

Mass, gravity, and the speed of light (3, Interesting)

wowbagger (69688) | more than 4 years ago | (#29913231)

OK, here's one for the physicists in the audience (and pardon the simplification of terms here, but...)

1) Being deeper in a gravity well slows time relative to being further out.
2) All things which have mass have gravity wells.
3) Photons have mass (NOTE TO THE CLUELESS: "mass" and "rest mass" are two different things - photons have no rest mass, but they most certainly have relativistic mass).
4) By 2 and 3 photons should have a (small) gravity well. More massive photons (higher energy and thus shorter wavelength) have deeper wells.

Thus, wouldn't 1 and 4 lead to higher energy photons "clocks running slower" (since they are deeper in a gravity well) and thus propagating as a lower speed as viewed by an observer outside their gravity well - and that effect would be negligible for all but the most massive photons.

(for the physicists: feel free to expand and clarify on the oversimplifications I've made here. This is, after all, targeting a Slashdot audience which has rather a wide spread of backgrounds).

Re:Mass, gravity, and the speed of light (2, Interesting)

mea37 (1201159) | more than 4 years ago | (#29913305)

"Thus, wouldn't 1 and 4 lead to higher energy photons 'clocks running slower'"

It's been too long since I've really looked at relativity for me to agree or disagree with this bit, but let's assume you're right...

" thus propagating as a lower speed as viewed by an observer outside their gravity well "

I think not. Your clock has nothing to do with how fast I see you moving. That's why it's your clock and not mine.

Uncertainty rule? (0)

Anonymous Coward | more than 4 years ago | (#29913269)

Didn't they already invalidate the results of the race by measuring it?

English is an imprecise language (0)

Anonymous Coward | more than 4 years ago | (#29913295)

I read that as "Intergalactic Race" (beings, êtres) not "Intergalactic Race" (racing, course).

Language sometimes is TOO simple.

more information (5, Informative)

bcrowell (177657) | more than 4 years ago | (#29913311)

This is actually just the latest in a series of measurements of this type. Since the Nature paper isn't free online, people may want to look at this [arxiv.org] similar paper from earlier this year that is available.

The article talks about testing "some theories" of quantum gravity. AFAIK the only theory of quantum gravity that makes anything like a prediction that could be tested in this way is loop quantum gravity [wikipedia.org] (LQG). The two leading contenders for a theory of quantum gravity are LQG and string theory. String theory essentially assumes a background of flat spacetime (plus an xtra 6 rolled-up dimensions), so I don't think it's capable of addressing the issue of whether spacetime is frothy at the Planck scale. LQG doesn't assume a background of flat spacetime, and in fact one of the main research programs in LQG is focused on showing that flat spacetime can emerge as a solution to LQG in the appropriate limit. LQG unambiguously predicts that the vacuum is dispersive, i.e., that the speed of light depends on the energy of the photon. However, LQG does not unambiguously predict the exact form of the energy-dependence. The possible form that is usually assumed in order to evaluate observational tests is |v/c-1|~(E/E_P)^n, where v is the speed of the photon, c is the speed of cause and effect in relativity (often referred to as the speed of light), E is the energy of the photon, E_P is the Planck energy, and n=1 or 2. Previous observations, such as the one in the arxiv paper I linked to above, have pretty much ruled out n=1, so if LQG is right, we'd presumably have to have n=2. Some people have been saying that LQG is ruled out by these measurements, but I don't think that's really correct, it's just constrained by them. Here [arxiv.org] is a paper by LQG researchers discussing the empirical tests, and they don't seem to be saying "OK, we give up." It's actually very exciting for people in quantum gravity to have observations that even have some chance of disproving a theory (or some version of a theory); the whole field is a dead end if it can never be tested by experiment.

In a broader sense, the holographic principle [wikipedia.org] gives strong, model-independent reasons for believing that spacetime is probably discrete, not continuous, at the Planck scale. Otherwise it's hard to imagine how there could be an upper bound on the information content of a given region of space. And any theory in which spacetime is discrete at the Planck scale will naturally give a dispersive vacuum. Therefore I'd say that either (a) we should eventually observe dispersion of the vacuum once the observations get sensitive enough, or (b) the holographic principle is telling us something that we don't yet understand.

Two good popular-level books that get into this kind of thing are Three Roads to Quantum Gravity by Smolen, and The Black Hole War by Susskind. Because Smolen and Susskind represent very different points of view on quantum gravity, anything that both books agree on is probably correct.

And the winner is... (0)

Anonymous Coward | more than 4 years ago | (#29913525)

Horse race announcer: It's a quantum finish! And the winner is-(Man holds up a board with the winning horse on it)
Horse race announcer: Harry Trotter!
Professor Farnsworth: No fair! You changed the outcome by measuring it!

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