Faster Than the Speed of Light: E = mc², Except When It Doesn't

NY Times ^ | 2/09/03 | George Johnson

[Boot Hill]

Other related FreeRepublic threads:
Will Spacecraft ever Go Faster than the speed of Light? (posted 2/16/03 by vannrox)

--Boot Hill

[txzman]

Hey, but everyone knows Science has it all figured out. Age of the Universe, no need of God, understanding of everything you need to know about mankind.

[ricpic]

"Theoretical physics is populated by some of the smartest people outside of Wall Street...."

He lost me right there.

[camle]

"Consider the horizon problem, a staple of popular science books. Look out (with a suitably powerful telescope) at a galaxy 10 billion light-years away. According to the logic of the Big Bang theory, the light was emitted 10 billion years ago and is just now reaching this part of the universe. Now turn around and look 10 billion light-years in the opposite direction. You have successfully observed two regions of the universe that themselves are 20 billion light-years apart. Since the whole universe is only 15 billion years old, they will never be able to see each other or (since nothing travels faster than light) interact in any way."

uh nope. if you beleive this then you beleive that by "looking the other way(direction)" we can see 10 million years into the future. if we look at another galaxy 10 million light years away, it still is in the past, which would put it as a contemporary of the first galaxy.

if all the logic in this story is this shoddy, then methinks he hath consumed too many wee cups.

[Boot Hill]

No camel jokes? Spoil sport!

camle:   "if you beleive this then you beleive..."

Not so quick. Think about it again. No presumption of "seeing into the future". The author has a valid point.

--Boot Hill

[camle]

if this is true, then by turing 90 degrees, you can see a 10 billion year old galaxy in real time. Your local direction is not a determinate as to which way light is flowing.

look at this less as a vantage point from a car on a road versus other cars, but rather as standing on the top of a mountain marvelling at how far below you things are.

the 10 billion year old light reaching earth from a galaxy that far away is from the past. it has to be since it reaches us. I suppose if you wait, you can catch more recent light waves, but that takes real patience:-).

(OK, so I'm a spoil sport.(sigh!))

[Dead Corpse]

Not quite. You still aren't getting it.

If you can look 10 billion light years in one direction, and 10 billion in the other, and the Universe is SUPPOSEDLY only 15 billion years old, then the two galaxies at either end would have still been 5 billion light years apart when the Big Bang supposedly went off.

Got it?

[Boot Hill]

I think you may be reading more into his words than he intended.

All he is saying is that two galaxies are separated by a distance of 20E6 ly in a universe only 15E6 ly old. Really not illogical when you consider that the two masses started traveling at high speed in opposite directions at the very beginning.

His conclusion, that those two galaxies will never be able to see each other or react with them in any way, is equally valid.

Boot

[AxelPaulsenJr]

Zeffrin Cochran could tell you that this guy is right.

[Dead Corpse]

Of course, that is also making the rather LARGE assumption the we here on Terra Firma are at the absolute center of the Universe.

Or are astronomers going to claim they have found the exact center of everything? If they are now making such a claim, it'd be the first time I've ever heard it. ;-)

[Ecliptic]

It didn't have to be light that traveled faster than light when the universe was created; the universe may have been created that far apart to begin with....

[Kevin Curry]

Zeffrin Cochran could tell you that this guy is right.

Ernst Mach might quibble a bit.

[bmwcyle]

You said it.

[Kevin Curry]

Of course, that is also making the rather LARGE assumption the we here on Terra Firma are at the absolute center of the Universe.

Of course it's the absolute center. Everywhere is the absolute center. Also the absolute edge.

[camle]

While this may imply that at least one of these galaxie is traveling faster than lightspeed, it remains plausible that they both may be 10 billion lightyears from earth, yet only 15 lightyears apart, or they may be travelling in opposite directions from the center.

I'm trying to recall high school geometry and trig here, but if we imagine the earth to be a point between two identical sides (10 billion lightyears long)of a triangle, and the ogirin somewhere along the opposite side (between the two galaxies), the distance between the origin and either galaxy (the other two points) may be up to nearly 20 billion light years, depending upon their angular distance from earth.

[Boot Hill]

DC:   "that is also making the rather LARGE assumption the we here on Terra Firma are at the absolute center of the Universe."

I don't think you need to make that presumption, just the observation of two galaxies, each 10E9 ly distant and both in opposite directions.

I guess what I'm missing is how we can view the light from any galaxy that is 10E9 ly distant in a universe only 15E9 years old. Even if that galaxy was moving at c, the age (since the big bang) would have to be twice that value or 20E9 years (time for the galaxy to arrive at that distant point, plus the time for the light to return to us).

--Boot Hill

[Sloth]

I don't know what's supposed to be so weird here. If 2 objects leave the same point at t=0, traveling in opposite directions at a speed of ~0.667c, then in 15 billion years they will be 20 billion light years apart. Big deal.

BTW, how do we know they didn't just *pass* each other at that point? :)

[Fury]

I'm OK with the premise of the article, but will butter still stick to my toast?

[Dead Corpse]

No. I understood that.

What I meant from my comments is that you never here astronomers saying "we can look 12 billion light years THAT way, but we can only see 3 billion light years in the other direction. This leads us to believe that the universe is only 15 billion years old."

From all the stories out there, it SEEMs like they looked in one direction 15E9 ly and said, "Well. I guess the universe is only 15E9 years old."

And yes, I fully realize that this probably isn't the case and that it probably reflects more on the piss poor nature of a reporters talents than it does on the hard science behind it.

[Boot Hill]

Sloth:   "I don't know what's supposed to be so weird here. If 2 objects leave the same point at t=0, traveling in opposite directions at a speed of ~0.667c, then in 15 billion years they will be 20 billion light years apart. Big deal."

Well, friend, the big deal is that it took 15E9 years to get that galaxy to that distant point and another 10E9 years for the light to get back to us and that is a total of 25E9 years in a universe only 15E9 years old!

Whooops!

--Boot Hill