Will they answer the question as what happened to the Doctor's Daughter? You'd think a military trained Time Lord would be helpful.

Brian Greene's Book Fabric of the Cosmos is pretty good. Read it a few years back.

/CSB or something.

That article was so riviting that I didn't even blink. But I kept looking to my left for some reason.

soporific: But I kept looking to my left for some reason

Take a step to the right.

Is this going to settle whether Fezzes are cool or not?

Does he talk about Midichlorians?

I hope it's better than Greene's "Elegant Universe" special.

so what is it?

When I place two flashlights back to back and turn them on, aren't the photons traveling at twice the speed of light away from eachother?

EdNortonsTwin: When I place two flashlights back to back and turn them on, aren't the photons traveling at twice the speed of light away from eachother?

jvl: soporific: But I kept looking to my left for some reason

Take a step to the right.

Put your hands on your hips.

stuhayes2010: Brian Greene's Book Fabric of the Cosmos is pretty good. Read it a few years back.

/CSB or something.

My old girlfriend from high school dated him briefly in grad school.

/and yeah, he's an excellent writer

threedingers: jvl: soporific: But I kept looking to my left for some reason

Take a step to the right.

Put your hands on your hips.

You bring your knees in tight...

/can't believe I'm polluting a theoretical physics discussion this way....

Edward Rooney Dean of Students: EdNortonsTwin: When I place two flashlights back to back and turn them on, aren't the photons traveling at twice the speed of light away from eachother?

[media.tumblr.com image 450x268]

no, no. You have a car moving at 45mph with the windows rolled down. A fly moving at 10mph manages to intersect with the car and makes it into the window. Both traveling straight lines. What happens to the fly? Does its path change at all? Get thrown back into the seat? ?

angry_scientist: Edward Rooney Dean of Students: EdNortonsTwin: When I place two flashlights back to back and turn them on, aren't the photons traveling at twice the speed of light away from eachother?

[media.tumblr.com image 450x268]

no, no. You have a car moving at 45mph with the windows rolled down. A fly moving at 10mph manages to intersect with the car and makes it into the window. Both traveling straight lines. What happens to the fly? Does its path change at all? Get thrown back into the seat? ?

yes?

angry_scientist: no, no. You have a car moving at 45mph with the windows rolled down. A fly moving at 10mph manages to intersect with the car and makes it into the window. Both traveling straight lines. What happens to the fly? Does its path change at all? Get thrown back into the seat? ?

Maybe?

EdNortonsTwin: When I place two flashlights back to back and turn them on, aren't the photons traveling at twice the speed of light away from eachother?

The distance between the photons is increasing at 2c, but at any reference you care to measure them, they are traveling at c themselves-- even relative to each other due to time dilation effects.

Fizpez: threedingers: jvl: soporific: But I kept looking to my left for some reason

Take a step to the right.

Put your hands on your hips.

You bring your knees in tight...

It's just a pelvic thrust...

/giggity?

Well, anything that has mass has gravity, and anything that has gravity distorts space/time, right?

Let's do the Time Warp again!???

I watched the NOVA series based off of his first book, but it only had a few chapters that were dry and cumbersome. Fabric of the Cosmos is etremely detailed and dry, but I still enjoyed it. It will be interesting to see if they can make any meaningful series out of it.

Man, subby, that headline got away from you.

EdNortonsTwin: When I place two flashlights back to back and turn them on, aren't the photons traveling at twice the speed of light away from eachother?

The fundamental axiom of special relativity is that the speed of light is always the same in any inertial frame of reference, so instead of the light going faster or slower (depending on the relative motion if the frame with respect to the light source), time itself slows down so that the observed speed of light (c) is always the same.

Picture a moving railway car moving at a substantial fraction of the speed of light, v. Inside the car there is a pulse of light bouncing up and down between two mirrors on the ceiling and floor. From the point of view of a passenger on the train, the beam travels the distance from floor to ceiling in time t₁.

A stationary observer sees the light pulse travelling in a zigzag trajectory due to the forward motion of the train. Each zig (or zag) is longer than the floor to ceiling distance, but since the observed speed of light is always c, it takes the pulse t₀ to travel this distance.

You can now draw a right angled triangle of base length vt₀, height ct₁ and hypotenuse ct₀.

Using Pythagoras to solve for the relationship between t₁ and t₀, you get

t₀ = t₁(1-v²/c²)^0.5

This factor (called gamma) shrinks to zero as v approaches c, making it impossible for any relative velocity between two moving frames of reference ever to exceed c.

Make sense?

Whoops, that should be:

t₀ = t₁(1-v²/c²)^-0.5

Time? Bah!

threedingers: time itself slows down so that the observed speed of light (c) is always the same

Just out of curiosity (I don't pretend to understand all of the math involved), why would time do this? Because it doesn't want to be hassled, or what?

Edward Rooney Dean of Students: threedingers: time itself slows down so that the observed speed of light (c) is always the same

Just out of curiosity (I don't pretend to understand all of the math involved), why would time do this? Because it doesn't want to be hassled, or what?

The faster you travel forwards, approaching the speed of light, the slower time moves for you.

Edward Rooney Dean of Students: threedingers: time itself slows down so that the observed speed of light (c) is always the same

Just out of curiosity (I don't pretend to understand all of the math involved), why would time do this? Because it doesn't want to be hassled, or what?

All of the weirdness that comes out of special relativity (time dilation, length contraction, lack of absolute simultaneity) is necessary so that the speed of light remains the same.

Nova?! No disassemble!

Jake Havechek: The faster you travel forwards, approaching the speed of light, the slower time moves for you.

Right, I get that. I've just always wondered "WHY?" The answer appears to be: "Because it does." Which I guess is good enough, I was just wondering if there was an actual reason.

Edward Rooney Dean of Students: Jake Havechek: The faster you travel forwards, approaching the speed of light, the slower time moves for you.

Right, I get that. I've just always wondered "WHY?" The answer appears to be: "Because it does." Which I guess is good enough, I was just wondering if there was an actual reason.

I can explain it in non mathematical terms, but I have to be baked. It is "just is", but there is a logic and beauty to it.

El Freak whither_apophis: so what is it?

I've never seen one before - no one has - but I'm guessing it's a white hole.

Uoy fo htob enod llew

/rsettib owt

I think we're all missing the important question:
Is it bigger on the inside?

SurfaceTension: Jake Havechek: The faster you travel forwards, approaching the speed of light, the slower time moves for you.

OK, the one thing I don't get is this...if I'm moving away from the earth at .99c, then only a few years will pass for me while many, many years will pass on earth. This, I get.

However, in my frame, I'm standing still and the earth is moving away from ME at .99c, so wouldn't time slow down for earth and (relative to earth) speed up for me?

Then at some future date we're re-joined, why wouldn't our relative times be the same?

I know experimentally, this isn't the case, but I'm really wondering WHY it isn't the case?

In order for the two of you to be re-joined, one of you has to undergo acceleration in order to match velocities. Now you have to take into account non-inertial frames of reference, i.e. accelerated or curved spacetime (aka a gravity well), when you calculate how much time has elapsed in either frame, the math for which is not as simple as for inertial frames. This unequivocally resolves which of you will be older and which will be younger.

SurfaceTension: DarnoKonrad: The distance between the photons is increasing at 2c, but at any reference you care to measure them, they are traveling at c themselves-- even relative to each other due to time dilation effects.

Thank you sir. More than 20 years after being introduced to the concept, you just gave me my "ah ha" moment of understanding of relativity. Time slows down for the photons, so relative to each other they are aging slower (or is it faster?).

If two spaceships move at near the speed of light their combined velocity will never exceed c as space and time will warp to prevent that from happening, and if you're a photon all of space and time will have collapsed to zero dimensions.

Photons don't 'experience' time the way we do (what we experience time to be is something of a mystery but whatever that is doesn't apply to photons) they are emitted and absorbed in the exact same instant we my perceive as a million years.

If you could send your wife through space at a speed that is faster than light, would her ass grow progessively smaller?

threedingers: SurfaceTension: Jake Havechek: The faster you travel forwards, approaching the speed of light, the slower time moves for you.

OK, the one thing I don't get is this...if I'm moving away from the earth at .99c, then only a few years will pass for me while many, many years will pass on earth. This, I get.

However, in my frame, I'm standing still and the earth is moving away from ME at .99c, so wouldn't time slow down for earth and (relative to earth) speed up for me?

Then at some future date we're re-joined, why wouldn't our relative times be the same?

I know experimentally, this isn't the case, but I'm really wondering WHY it isn't the case?

In order for the two of you to be re-joined, one of you has to undergo acceleration in order to match velocities. Now you have to take into account non-inertial frames of reference, i.e. accelerated or curved spacetime (aka a gravity well), when you calculate how much time has elapsed in either frame, the math for which is not as simple as for inertial frames. This unequivocally resolves which of you will be older and which will be younger.

Which explains time dilation in the vicinity of black holes, too. It's neat how both of those phenomena come out of the same math.

TravisBickle62: If you could send your wife through space at a speed that is faster than light, would her ass grow progessively smaller?

No, but it won't sag as soon. When she comes back, her body will still be tight, but you'll be an old man.

Jake Havechek: TravisBickle62: If you could send your wife through space at a speed that is faster than light, would her ass grow progessively smaller?

No, but it won't sag as soon. When she comes back, her body will still be tight, but you'll be an old man.


No, she'd kill her father-in-law before her husband was born to deliver the punch-line about her butt getting smaller.