Matter Discovered Traveling at Near Light Speed

mcgrew writes to mention New Scientist is reporting that scientists have clocked matter traveling at 99.999% the speed of light. "The fastest flows of matter in the universe shoot out of dying stars at more than 99.999% the speed of light, new observations reveal. When a massive star runs out of fuel, it collapses to form a black hole or a neutron star. In the process, some of the matter from the star also explodes outward at blistering speeds, producing an intense burst of gamma rays and other radiation."

Kudos to the editor

[Anonymous Coward]

Much better subject line than what was found in The Firehose...

(The original subject line said "Matter found travelling at the speed of light", or something along those lines.

Close != At.

Given all the Complaints and BS the mods have to put up with sometimes, I think they should get complimented for a job well done as well.

Re:

[Tofystedeth]

They could have done even better. How about "Really damn close to speed of light." Though I guess at that speed, .001% is still a hefty amount of m/s.

Re:Kudos to the editor

[It doesn't come easy]

Actually, the speed was calculated to be 99.9997% but there was a rounding problem when the report was generated via their new-fangled AI system and the system kept crashing from the unexpected logical impossibility...

Re:

[larpon]

You Gentoo folks always have only one answer TO EVERYTHING DAMNIT!1! DAAMNIT!!1

Blistering speeds?

[Anonymous Coward]

What exactly does that scientifically mean?

THANKS SLASHD0T FOR YOUR PR0FESSIONALISM!!

Re:Blistering speeds?

[forrestt]

It's the speed at which an object in a vacuum must travel to spontaneously get blisters to appear on its surface. What did you think it meant?

Re:

[KDR_11k]

That's between laughable speed and ludicrous speed.

Re:Blistering speeds?

[FrameRotBlues]

You mean between ridiculous speed and ludicrous speed, right? Wasn't that the order on Spaceballs? Light Speed, Ridiculous Speed, Ludicrous Speed?

Re:Blistering speeds?

[drkich]

Please, for the sake of Scientific completeness, do not forget PLAID!

Re:

[somersault]

Laughable speed is the speed limit on UK motorways - 70mph.

Please do not try to enforce all humour to follow a strict set of rules. While it may seem that rules help to control the fun at first, in the end they only stifle your donut making skills.

Re:Kudos to the editor

[Ed Avis]

Infinite nines (99.999.... per cent) would be the same as the speed of light. I say this only to have an excuse to link to a list of proofs that 0.9 recurring equals 1 [qntm.org].

To be clear...

[brian0918]

We've known about gamma ray bursts for a long time. It's just that now we know how fast the matter is moving that causes these bursts.

Re:

[ajs]

Didn't we already know about superluminal motion [wikipedia.org] (which turns out to be near-speed-of-light motion, viewed oddly), active galactic nuclei [wikipedia.org], etc.? What's the new info, here or is it just confirmation of what we'd known before?

99.999%

[Trigun]

Slackers.

Re:99.999%

[hkgroove]

Well, report back to us when your contrails are plaid.

Re:99.999%

[the dark hero]

That's Ludicrous!

Re:99.999%

[snowgirl]

I had a friend playing Silent Hunter, it was a German one, and when he put the boat into full speed ahead, they were saying "Wahnsinnige fortfahr aus!" I really had to listen to it a few times just to be sure. Then I confidently told him that one of the possible translations of that was "ludicrous speed".

He also got a kick out of "periscope" being literally "see-pipe" in German.

I know what it is, I know what it is!

[AltGrendel]

It's the Planet Express ship [wikipedia.org]!

Re:

[jshriverWVU]

It's the Planet Express ship [wikipedia.org]!

No need to link to a description. This is /. we all know! lol I can't wait till the new season of Futurama starts. Bender is hilarious.

99.999% Of the speed of light

[Timesprout]

will be snails pace when we get warp technology.

Re:

[drinkypoo]

Maybe in the star trek world, but not in Einsteins.

The confirmation of general relativity doesn't prove that it works in all cases.

What's the speed of force?

[TheBearBear]

Hey guys, let's say you have a 500 foot pole out in space, far away from anything (no friction, nothing). you are on one end of the pole, and i on the other. Then i push the pole towards you. When does the other end of the pole move towards you, after MY END MOVES? is it instantaneous? or does it take .000000005 seconds of whatever. Like the atoms of the pole push each other on and on and so forth till it gets to the end. if it does take time, is it faster than light, or slower? what if the pole was 300,000,000 meters long? does it take about 1 second for u to notice the other end moves?

Re:What's the speed of force?

[The_REAL_DZA]

The only way you'd get a superluminal effect is if you had a perfectly rigid pole (and, seeing as how this is Slashdot, I'm going to discount that possibility.)

Re:What's the speed of force?

[Anonymous Coward]

I know you're joking, but even a perfectly rigid pole would be subject to the propagation of forces. Think about what forces have to propagate in order to tell the other end of the pole to move. One atom has to repel the next atom using electromagnetic force, weak and strong nuclear forces, which has to in turn repel the next atom, etc, etc. There is an elastic repulsive process which goes all the way down the pole until it reaches the other end. And we know the fastest that this can happen is the speed of light. So the pole will be momentarily compressed as the force propagates.

No information can travel faster than the speed of light, as a general rule.

Re:What's the speed of force?

[Hatta]

What you're saying essentially is that there's no such thing as a perfectly rigid pole.

Re:

[ArsonSmith]

I'm sure there are plenty of ridged poles around. Just very few of them are used.

Re:

[ArtuRocks]

And which fundamental law of the universe is the one that dictates good use of a rigid pole requires more than one entity?

Re:What's the speed of force?

[totallygeek]

Hey guys, let's say you have a 500 foot pole out in space, far away from anything (no friction, nothing). you are on one end of the pole, and i on the other. Then i push the pole towards you. When does the other end of the pole move towards you, after MY END MOVES? is it instantaneous? or does it take .000000005 seconds of whatever. Like the atoms of the pole push each other on and on and so forth till it gets to the end. if it does take time, is it faster than light, or slower? what if the pole was 300,000,000 meters long? does it take about 1 second for u to notice the other end moves?

Do not try to push the pole. That's impossible. Instead, only try to realize the truth: there is no pole. Then you'll see, it is not the pole that is pushed, it is only yourself.

Re:

[Anonymous Coward]

Do not try to push the pole. That's impossible. Instead, only try to realize the truth: there is no pole. Then you'll see, it is not the pole that is pushed, it is only yourself.

Woah!

Re:What's the speed of force?

[whimmel]

Woah!

I can see why this hasn't been modded up yet. Too much emotion in your impression. Whoa.

Re:

[nbritton]

Hey guys, let's say you have a 500 foot pole out in space, far away from anything (no friction, nothing). you are on one end of the pole, and i on the other. Then i push the pole towards you. When does the other end of the pole move towards you, after MY END MOVES? is it instantaneous? or does it take .000000005 seconds of whatever. Like the atoms of the pole push each other on and on and so forth till it gets to the end. if it does take time, is it faster than light, or slower? what if the pole was 300,000

Re:

[sk8king]

I have often had the same thought, except in my mental experiment, there is a rope instead of a pole.

Re:

[mcmonkey]

I have often had the same thought, except in my mental experiment, there is a rope instead of a pole.

In your mental experiment, you're pushing a rope?

Re:What's the speed of force?

[veganboyjosh]

I think he's just yankin' your chain.

Re:Speed of sound

[Anonymous Coward]

It will be whatever the speed of sound is in the pole. Assuming a perfectly rigid material it would be instant, but there is no such thing and the actual speed will much less than c.

Speed of Gravity

[drgonzo59]

What if it is the gravitational field that changes. Say the sun disappeared or exploded, would we find out about it immediately or after so many minutes. In other words, do the gravitational field disturbances also propagate at the speed of light?

Re:Speed of Gravity

[EMeta]

Yeah, Gravity moves at the speed of light. That's all part of general relativity.

Re:

[WaZiX]

That same question was what got Einstein started in the first place actually....

Re:Speed of Gravity

[MindStalker]

Whats funny is if the sun imploded you would never know (except for the loss of light of course) because you would be the same distance from the center of mass with the same total mass.

But as other guy said, yea gravity propagates at the speed of light. We can test this (with precise instruments) because you can measure the pull of the moon easily. If gravity propagated instantly the moon would be pulling from an angle that would be 1.28 seconds ahead of where the moon appeared to be.

Consider the force involved

[benhocking]

If you were to push a 600,000 km pole 4 meters over a period of 1 second, then you've probably exerted a lot of force (pressure) in order to do so. Imagine that the pole weighs 100 grams per meter (i.e., it's fairly light). That pole has a total mass then of 60,000,000 kg. Assume that the force/acceleration is uniform, and you find that 4 meters over 1 second (starting from rest) requires an acceleration of 8 m/s^2. That implies a total force of 480,000,000 Newtons or about 108 million pounds of force. Not

Re:

[ArsonSmith]

Not really. At that length the pole would be like pushing a wet noodle. The other end may never move.

Re:

[Tofystedeth]

Thank you. You brought a wonderful image to mind of Archimedes in space, pressing on a gigantic pole, and having the end spring back sending him caroming around the solar system.

Re:

[Tofystedeth]

Actually, by my understanding of it, the pole would only be 599,999,996 at the exact moment the other end begins to move. The rest of the time it is either shrinking to that length, or growing to it. This only even applies if you push it 4 meters in less than 2 seconds. More than 2 seconds and the other end will have started moving before you reached full compression. Unless you were able to instantaneously push the end of the pole, then it would simply be growing for the full 2 seconds.

Re:Speed of sound

[NMerriam]

That is to say, it shrunk? isn'tthat weird???

Not really. Take a brick of Jell-O. Push one end. You'll move it, but it will distort in shape, compress, wobble, send waves, etc.

The only difference between Jell-O and every other solid substance is that your eyes and brain just aren't precise enough to see at a small scale that they are all behaving the same way, just to different degrees.

Re:

[pipingguy]

Not really. Take a brick of Jell-O. Push one end. You'll move it, but it will distort in shape, compress, wobble, send waves, etc.

Boobs also act similarly. Or so I've heard.

Eureka, that's it! Boobie physics! What else could better attract young males to science and fluid dynamics?

Re:

[SocietyoftheFist]

isn'tthat weird???

That you are dutch???

Sorry couldn't resist.

Re:

[zCyl]

That is to say, it shrunk? isn'tthat weird???

It's not really as weird as it sounds. Try this with a basketball (the rubbery version of this), and you will see shrinking easily with your eye. A pole is simply more rigid, but if you push it fast enough and hard enough to cause that compression, that's exactly what you'll get. If you apply force to the front of a free-floating car sufficient to cause motion before the speed of sound can propagate the energy, then you get a crumpled bumper. This is the same

Re:What's the speed of force?

[Barterer]

The "speed of force" as you put it, is not really a speed inherent to force. You would be measuring how fast a tensile or compressive wave passes through the pole, same as the speed of sound through it. It would be much slower than the speed of light.

Re:

[JesseL]

Your shove on the pole would travel down it's length as a compression wave. I'm not sure but I suspect the the wave would travel at the speed of sound in whatever your pole was made from (if it was steel @ 4500 m/s it would take 1,111.1 hours for the compression wave to travel 3,000,000 meters)

Re:What's the speed of force?

[Russ Steffen]

I asked this question in a physics class and the answer I got, which makes quite a bit of sense, is that force travels through a material at the speed of sound. So if in your example your 500 foot pole was made of steel, the opposite end starts moving roughly 30 milliseconds after you push the near end. (The speed of sound in steel is very roughly 5000 meters/sec.)

Re:

[magarity]

The speed of sound in steel is very roughly 5000 meters/sec
 
So if you fire said steel pole out of a rail gun with a 10,000m/sec muzzle velocity the pole would come out -500 feet long?

Re:

[JesseL]

Only if all the force of the rail gun is applied to only the back end of the pole. If the force is applied equally to the entire pole at once, there shold be no distortion.

Re:

[NMerriam]

So if you fire said steel pole out of a rail gun with a 10,000m/sec muzzle velocity the pole would come out -500 feet long?

I'm pretty sure the entire object has to be accelerated before it can leave the muzzle.

Re:

[alzoron]

The steel pole isn't going to have a constant compression rate. As the pole is compressed more and more its density increases thus changing the speed of sound through it. Both ends of the pole would likely "catch up" with each other before we experienced any major space-time paradoxes that destroyed the universe as we know it.

Re:

[a_ghostwheel]

You're assuming that shooting steel pole from a rail gun is equivalent to pushing one end of it. Most likely it is not. However if for the sake of discussion we'll assume that you just bumping something into the generic steel pole at the speed of 10km/s, I highly doubt we will be talking about elastic deformations at this point - thus same model of compressed wave propagation will no longer apply.

Re:

[wanerious]

In physics, we usually model the atoms in the solid pole as connected by stiff springs. The speed of communication of a force between one end and the other would depend on the stiffness of the springs (or, realistically, on the rigidity of the material the pole is made of). This is usually defined to be the speed of sound in the material, and it is typically much, much less than the speed of light.

Re:What's the speed of force?

[Cadallin]

Wow, I was hoping that there would already be an explanation answering this, but here you go: The speed of "force" as you put it, is actually quite slow. It's a actually the speed of sound through the object. Why? Because when you push the rod, you're bumping the molecules, they have to push the molecules in front of them, and on until you reach the end. This is actually a sound wave propagating the medium, you just usually can't hear it. Now, if you had a perfectly rigid pole (cue penis jokes here) it would seeming move instantly. However, no known substance is anywhere close to perfectly rigid. Even atomic nuclei, which are, far, far more rigid than bulk matter, behave like drops of fluid and can have waves propagate through them. So no, you can't forge a pole to another planet and communicate instantly, it would be hugely slower than normal radio.

Re:

[lelitsch]

Way before you run into any relativistic effects--or even the speed of sound inside the pole--basic 17 century Newtonian physics [wikipedia.org] will make the process less than instantaneous.

Also, thanks to Newton's Third Law, space is like Soviet Russia: In space, the pole pushes you [utk.edu].

Re:

[EMeta]

To oversimplify: Most solid matter has some stiffness. You know, like springs' K. Even the most brittle objects bend a bit. (Glass, say, has an extremely large stiffness.) Now model your rod like a system of two balls connected by a spring. [ O--VVV--O ] If you push one end (then stop), the other end will move, and eventually return to the same equilibrium (given no other forces applied). the time it takes to propagate the force, as you can probably now see, is determined by the spring's stiffness (

Re:

[maz2331]

I'd expect the physical force would travel along the pole at it's local speed of sound in the material that the pole is made of. The pole's molecules have some space between them and are attracted to one another such that you have a solid. Therefore, pushing on one part of the pole will slightly compress the pole's material until the newly repositioned molecules bump into their neighbors and cause the motion to be propagated. If you try to accelerate the pole too quickly (faster than its local speed of s

Re:What's the speed of force?

[gatkinso]

>> is it instantaneous

No. Imagine a train at rest. The engineer decided to back up. Boom boom boom go all the cars in sequence as the slack between them is eliminated by the cars compressing together. Finally, the caboose moves. Same deal with matter, but on a much smaller and faster scale, involving molecules and atoms.

Re:

[Hugonz]

The speed of any interaction is slower that the constant c (speed of light in the vacuum) This is one of the consequences of General Relativity.

Is the sun exploded right now, that earth would start drifting into space ONLY after about eight minutes, which is the time it takes to the sunlight to reach us.

Re:

[Tofystedeth]

uh, no. Speed of sound in steel is approx. 4500 meters/second.

Which is

much, much less than the speed of light.

I'm not sure why you are contradicting the fact that 4500 299,792,458.

cool

[FudRucker]

now all we need is to capture a sun in supernova mode to power out space ships, hope it has a good fuel tank...

This is not new...

[mbone]

"Superluminal [wikipedia.org]" expansion from Quasars have been known since the 1960's. (They appear to be superluminal, i.e., faster than light speed, as they are so close to the speed of light that time dilation becomes important.)

Red-shift?

[bugnuts]

"But officer, the light looked green!"

Re:Red-shift?

[PhxBlue]

"But officer, the light looked green!"

I tried that and got a citation for speeding instead. Do you have any idea what the fine is for going 201,184,560 mph in a 35-mph zone?

Re:

[argStyopa]

You should fight that. If you were traveling what, about 16% of the speed of light toward the stoplight, that "red" light (650nm) would have appeared "green" (550 nm) to you.

Not to mention that there would probably have been relativistic effects making your speed (from your viewpoint) and your speed (from the cop's viewpoint) significantly different!

Re:

[digitig]

"But officer, the light looked green!"

"Then I'm afraid I'm going to have to give you a ticket for exceeding a hundred-million miles per hour in a built-up area."

I am a genius

[nomadic]

If I stood on some of this matter that was flying out of a sun, and shot a bullet in the direction I was going, that bullet would break the speed of light!

Re:

[gatkinso]

No. It would not. The bullet would appear to do many different things, depending on your frame of reference.

None of them involve the bullet appearing (or actually) attaining or surpassing the speed of light regardless of the frame of reference.

Re:

[Zaatxe]

If I stood on some of this matter that was flying out of a sun, and shot a bullet in the direction I was going, that bullet would break the speed of light!

No, because 0.001% of the speed of light is still 300,000 meters per second. I don't believe you will find a gun that shoots a bullet that fast.

But you have an interesting theory there, nonetheless. I once asked myself what would happen if two space ships flying at 70% of the speed of light and one cross the another, flying in opposite directions. Si

Re:

[gatkinso]

on each ship, the other appears to be appraoching at a speed approaching the speed of light.

on a 'stationary point between, each ship appears to be approaching at thier respective speed, but the rate of closure appears to be approaching the speed of light.

I think that is how it goes.

I know, makes no sense except to the guy whose avatar is beside this story!

Re:

[zCyl]

on a 'stationary point between, each ship appears to be approaching at thier respective speed, but the rate of closure appears to be approaching the speed of light.

Not quite. From the perspective of an observer between them, each ship appears to be approaching at 70% of the speed of light, and the apparent relative difference in speeds from that middle observer's perspective is 140% of the speed of light. However, this does not violate anything in special relativity, since the 140% is only an apparent rel

Re:

[Wooster_UK]

What happens is that velocities don't add together using the simple addition rule. See the Wiki [wikipedia.org]. Once you're at reasonable fractions of the speed of light (say about 10%; certainly by the time you hit 50%), the fact that it's not simple addition makes an appreciable difference. In your example, each space-ship measures the other as going at about 94% of the speed of light.

Re:I am a genius

[wanerious]

What really happens is that velocities don't add like that. They seem to for everyday objects, but relativistic effects become important at 0.7c. You should add them according to the Einstein formula: v = (B+v')/(1 + Bv') where B is the speed of one ship relative to an observer at rest (0.7c), and v' is the speed of the other ship in it's frame (0.7c). So the speed of one ship relative to the other is just v = 1.4/1.49 = 0.94c. You can see that, for small speeds, the product in the denominator is small, so we have the usual addition.

Re:

[xPsi]

What really happens is that velocities don't add like that. They seem to for everyday objects, but relativistic effects become important at 0.7c.

Your post is right on. I might add that when relativistic effects become important for everyday objects might be a matter of application. For example, some GPS systems need to account for relativistic effects for the relativive motion of objects in orbit with respect to the surface of the earth (moving much smaller than 0.7c). It depends on the accuracy requ

Re:

[FedeLebron]

Nope. Time dilation and space contraction take place here. Relativity states that if, say, you were going at 75% of the speed of light, and shot a missile at 50% the speed of light, neither you, nor the torpedo, nor a 3rd observer would see the torpedo go faster than light. They'd see it go juuust under c, about 95% of c. In relativity, adding of velocities isn't as simple as absolute v + relative v, it's an asymptotic function that means you never actually reach the speed of light.

Re:

[drxenos]

No, it wouldn't.

Re:

[MontyApollo]

>>If I stood on some of this matter that was flying out of a sun, and shot a bullet in the direction I was going, that bullet would break the speed of light!

Or better yet, turn on a flashlight. Light would break the speed of light!

Re:

[nomadic]

Oh. My. God.

I cannot believe how many people wrote serious responses to a non-serious post.

I was originally going to put in an "its a joke" disclaimer at the bottom, but I thought that would be silly, nobody would think I was serious, so I instead made the "I am a genius" subject line to indicate that it was meant to be humorous.

If you can't tell dumb physics jokes on Slashdot, then I guess you really can't tell them anywhere.

Re:

[PhxBlue]

If you can't tell dumb physics jokes on Slashdot, then I guess you really can't tell them anywhere.

If you don't want serious responses, you should try to make your dumb physics jokes actually funny. :)

Re:

[WaZiX]

That's exactly what the general theory of relativity proved would _NOT_ happen. From wikipedia article: "The speed of light in a vacuum is the same for all observers, regardless of their relative motion or of the motion of the source of the light". http://en.wikipedia.org/wiki/Theory_of_relativity [wikipedia.org]

Microblackholes?

[zymano]

Could this create blackholes?

microblackholes = Dark matter?

my Tachi joke

[phrostie]

Boom Boom Boom,

fire the tachion cannon!

Beating the previous record...

[jpellino]

of chairs flying through meeting rooms in Redmond WA.

Why?

[LordKaT]

Why in the world did I read "Matter Discovered" as a name?

Huh?

[DoofusOfDeath]

Why is this news? I read this article ten minutes from now.

Re:

[brunascle]

TFA answers just that:

but when it starts colliding with surrounding gas, it creates afterglows in visible and infrared light... [they measured] peaks of 153 and 180 seconds

turns out, the times it takes to produce the afterglow is actually what they use to measure how fast it was moving.

Re:Light is particles...

[brunascle]

yes, light is particles, called photons. they are massless, which is what i believe allows them to move at the speed of light. and they always move at the speed of light too. i believe, in order to move at the speed of light, you must have always been, and always will, move at the speed of light. at light speed, time doesnt move, so you cant get out of light speed because that would require time to do so. i think it works the other way too.

Re:Light is particles...

[gatkinso]

Actually, and believe you me I am no damn physicst (can't even spell it), a photon has no "resting mass", but does have momentum, which implies that there is an upper limit to is mass which cannot be zero.

WTF does that mean? Dunno. OK screw that. No more Wiki for me.

Re:Light is particles...

[klaun]

For example, those little thingies with the black and white paddles in them that look like light bulbs from middle school science class work on the idea that photons transfer and take momentum from stuff they interact with. Momentum is a quality very closely tied with mass.

Crookes radiometer (the aforementioned little thingy with the black and white paddles) does not rotate due to light imparted momentum (the force is too small). This theory of the rotation is disproved by the fact that after a certain point making the vacuum in the bulb stronger reduces the effect, which is the opposite of the expected result if the rotation was due to radiation force.

The actual forces responsible for rotation are a combination of forces due to molecule movement between the hot and cold sides of the vanes near the edges. Wikipedia has a good write up about it here [wikipedia.org].

There is an invariant mass for an object, i.e. a quantity that remains the same in all reference frames. This can be calculated based on energy and momentum. True of photons as well. Photons don't have a rest mass because rest mass is defined as the mass of an isolated and at rest relative to the observer object. Photons can't be at rest relative to an observer (and if they are isolated they are travelling at c).

Re:

[GrayCalx]

Like the other replier said, at light speed there is still time. If you were to travel the speed of light, you'd still notice/experience the passing of time, its just the experience of time relative to some one else, or more specifically someone not in your reference frame, thus relativity.

Also, light can be slowed down depending on what medium its passing through. And I would hazard a guess that the commonly used term "speed of light" or c, is based on the speed of a light photon in a vacuum, and that

Re:

[brunascle]

no you wouldnt. at the speed of light time stands still. outside of your reference frame, yes, time would still exist but you could not experience it because that would require time. you'd be completely still, unable to move. the universe would pass by instantaneously.

yeah, i forgot light changes speed in some mediums. not sure how that fits in to relativity though.

Re:

[Sporkinum]

According to the show "Universe" which is showing on the History Channel now. If a gamma ray burst from a quasar hit the earth, it would boil off the ozone layer and basically kill the planet. I believe they said the likelyhood of that happening was 1% of the lifetime of the earth, whatever that really means. Was kind of a cool show, but had lots of the boogie man universe is gonna get ya. Kind of irritating actually.

Re:

[lazlo]

Well, yes, but the gamma ray burst is traveling at 100% of the speed of light, it being light and all. So the matter, travelling at 99.9997% of the speed of light, is trailing the gamma rays by an extra .000003 lightyears (94 light-seconds) every year.

So yes, the event happened 1 million years ago. The gamma rays took 1 million years to travel the distance, and arrived this year. The matter takes 1,000,003 years to make the same trip, and so it will arrive in 3 years.

Re:

[ArsonSmith]

that happens, and that. There's another one. Again. Another.

the point is, basically nothing. It happens all the time.

Incorrect

[BlackGriffen]

We think it's time goes slow, it thinks our time goes slow. It's one of the symmetries of a Lorentz transformation. What happens is that when one of the observers accelerates so that it can sit down and compare notes with the other observer the observer that did the accelerating will have seen less time go by. It's a peculiarity of the geometry of spacetime that an inertial observer takes the path of longest proper time, that is the time that the observer will see go by.

Re:

[geekoid]

If we had a device that could send a signal to earth from that star at the moment it expels this matter, we would have about 8 hours and 45 minutes. That's how much a radio signal traveling at the speed of light would beat the particle traveling at 99.999% at speed of light over 100 LY. If the signal isn't moving at exactly the speed of light, then we would have no warning at all.

Re:

[Achoi77]

I thought about this when I was younger. I came to the conclusion that it would probably react similarly to a water hose. Shoot it in one position, but move the trajectory, and quickly enough, the 'beam' of water bends. This time instead of water think: light shooting out. Sure it can 'bend,' but we are unable to see far enough to tell the difference.