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[7imz]

1. why is it that we can neve reach the speed of light?

2. somebody please explain the twins pardadox (you have a pair of twins, one stays on Earth, and the other one travels around space at something close to the speed of light. When he returns to Earth after 50 years or so, his brother would appear to be much older than him)

 

[demon]

I have a sudden urge to watch the Carl Sagan Cosmos series again...

 

[robertsan21]

1. why is it that we can neve reach the speed of light?

we dont have a engine that can generate that much energi yet,and besides would you want to travel at lightspeed when your going to your local wall mart? before you hit your breaks you been around the earth 10 times.

but good news, i think volvo is working on one called the flux compasitor 2

2. somebody please explain the twins pardadox (you have a pair of twins, one stays on Earth, and the other one travels around space at something close to the speed of light. When he returns to Earth after 50 years or so, his brother would appear to be much older than him)

hmm well my GF has a twin sister but they never traveled around space yet

 

[Azih]

hmm well my GF has a twin sister

Dude... pics.

 

[Dilbert]

1. why is it that we can neve reach the speed of light?

Transformations in special relativity use the Lorentz factor, usually denoted by the Greek letter gamma:

The energy of an object is given by E = (gamma * rest mass)c², where gamma is the Lorentz factor. As v -> c, gamma goes to infinity...which means that it would take infinite energy to accelerate a particle with mass to the speed of light. (Of course, particles with zero rest mass like photons are not subject to this limitation, so they can travel at exactly the speed of light.)

2. somebody please explain the twins pardadox (you have a pair of twins, one stays on Earth, and the other one travels around space at something close to the speed of light. When he returns to Earth after 50 years or so, his brother would appear to be much older than him)

A stationary observer observes that the clock in a moving frame of reference seems to run more slowly. Since there is no preferred frame of reference, you might think that the two twins would each see the other as "moving," and therefore not have a real age difference. However, the moving twin really is different, since he/she experiences accelerations during the trip, which is why the "paradox" emerges.

 

[JoshuaJSlone]

A stationary observer observes that the clock in a moving frame of reference seems to run more slowly. Since there is no preferred frame of reference, you might think that the two twins would each see the other as "moving," and therefore not have a real age difference. However, the moving twin really is different, since he/she experiences accelerations during the trip, which is why the "paradox" emerges.

This is the bit that always throws me off. As you've already mentioned, there is no exact frame of reference... so why is it that the one twin is really accelerating?

 

[shakezula]

nm

 

[sc0la]

YOu can never catch light. If a ball travels 10 MPH and you travel 9 MPH it will appear to travel away from you at only 1 MPH

This is not true with light, If you were to travel at 90% the speed of light it does not appear to go slowly, infact light still moves away from you at the speed of light regardless of how fast you are moving.

The reason massless particles like light can move so fast is percisely because they have no mass. You having mass requires energy input to move, as you accelerate faster and faster you require more and more, and as you approach the speed of light the amount of energy required increases exponentially and approaches infinite. You can never power a speed of light engine is one problem.

Secondly being a being with physical size, and vulnerability to damage, when traveling the speed of light tiny particles of dust in space become capable of delivering lethal blows when traveling at near light speed, the entire universe would become an innavigable minefield of supervelocity space shit.

As for B it is a bit more complicated, but just imagine that time physically slows when you are traveling at increasing speeds, and this has nothing to do with super speed. YOu actually age slower running around a sofa than the person sitting on the couch, but since the differences are so small and the time periods are so short you won't be able to measure the difference.

 

[robertsan21]

Dude... pics.

abit of topic here but if these two twins where to travel at lightspeed i guess their good looks would not be needed

My GF

her sister

 

[Dilbert]

This is the bit that always throws me off. As you've already mentioned, there is no exact frame of reference... so why is it that the one twin is really accelerating?

I don't claim to understand it quite so well myself, but here goes. One of the deep principles underlying general relativity is that acceleration (of whatever kind) and the effects of gravity are indistinguishable. "Acceleration" is the observed result of a curved/warped space-time that we instinctively think of (incorrectly) as "flat."

In the case of a rocketship blasting off from a planet, the underlying physics is pretty simple: the rocket generates thrust in one direction, and by Newton's Third Law, the planet experiences an equal force in the opposite direction. However, due to the vast mass difference between the planet and the rocket, only the rocket undergoes a significant acceleration...which means that only THAT twin travels through curved space-time and experiences the real effects of time dilation.

P.S. Does anyone think Einstein would have been pimp enough to hook up with either of the girls in this thread?

 

[JoshuaJSlone]

I don't claim to understand it quite so well myself, but here goes. One of the deep principles underlying general relativity is that acceleration (of whatever kind) and the effects of gravity are indistinguishable. "Acceleration" is the observed result of a curved/warped space-time that we instinctively think of (incorrectly) as "flat."

In the case of a rocketship blasting off from a planet, the underlying physics is pretty simple: the rocket generates thrust in one direction, and by Newton's Third Law, the planet experiences an equal force in the opposite direction. However, due to the vast mass difference between the planet and the rocket, only the rocket undergoes a significant acceleration...which means that only THAT twin travels through curved space-time and experiences the real effects of time dilation.

Ahh, that actually helps a great deal in trying to visualize things.

P.S. Does anyone think Einstein would have been pimp enough to hook up with either of the girls in this thread?

Do they really hold a candle to these fine wives?

 

[WHOAguitarninja]

I don't claim to understand it quite so well myself, but here goes. One of the deep principles underlying general relativity is that acceleration (of whatever kind) and the effects of gravity are indistinguishable. "Acceleration" is the observed result of a curved/warped space-time that we instinctively think of (incorrectly) as "flat."

In the case of a rocketship blasting off from a planet, the underlying physics is pretty simple: the rocket generates thrust in one direction, and by Newton's Third Law, the planet experiences an equal force in the opposite direction. However, due to the vast mass difference between the planet and the rocket, only the rocket undergoes a significant acceleration...which means that only THAT twin travels through curved space-time and experiences the real effects of time dilation.

P.S. Does anyone think Einstein would have been pimp enough to hook up with either of the girls in this thread?

Only if he could accelerate past the speed of light to get here alive =).

(btw....jinx, check back in that physics help thread.....i NEED you man....and btw...)

 

[Chipopo]

we dont have a engine that can generate that much energi yet,and besides would you want to travel at lightspeed when your going to your local wall mart? before you hit your breaks you been around the earth 10 times.

but good news, i think volvo is working on one called the flux compasitor 2



hmm well my GF has a twin sister but they never traveled around space yet

This is why fashion models are not physicists.

Spoiler

*Wishes he was either*

 

[robertsan21]

This is why fashion models are not physicists.

Spoiler

*Wishes he was either*

yeah i know we models have no brain, just ask my very good friend Derek zoolander

 

[NLB2]

Transformations in special relativity use the Lorentz factor, usually denoted by the Greek letter gamma:

The energy of an object is given by E = (gamma * rest mass)c², where gamma is the Lorentz factor. As v -> c, gamma goes to infinity...which means that it would take infinite energy to accelerate a particle with mass to the speed of light. (Of course, particles with zero rest mass like photons are not subject to this limitation, so they can travel at exactly the speed of light.)


A stationary observer observes that the clock in a moving frame of reference seems to run more slowly. Since there is no preferred frame of reference, you might think that the two twins would each see the other as "moving," and therefore not have a real age difference. However, the moving twin really is different, since he/she experiences accelerations during the trip, which is why the "paradox" emerges.

If photons have no mass, how come light is affected by gravity?

 

[AntoneM]

gravity curves space and time.
photons travel through both space and time.
therefore gravity affects photons.

 

[Hitokage]

NLB2: Because gravity is an effect on space, not simply an attraction between masses.

 

[Boogie]

we dont have a engine that can generate that much energi yet

Way to break down the stereotypes

 

[Particle Physicist]

abit of topic here but if these two twins where to travel at lightspeed i guess their good looks would not be needed

My GF

her sister

you have any pictures of you with any of these girls you keep posting?

 

[7imz]

another question...

what about tachions (sp?), how come they travel faster than the speed of light?

 

[missAran]

abit of topic here but if these two twins where to travel at lightspeed i guess their good looks would not be needed

My GF

her sister

This thread just got ten times cooler and ten times less nerdy.

I feel bad about saying that. To girls in the forum: disregard that. You are beautiful creations and are fine the way you are. Do not ever feel the need to look like those girls up there. Piggish guys (like all of us) and society will try and force a "type of beauty" on you, that doesn't mean anything. Your character is what truly matters and what will last forever -- although you are all physical beauties, your character is truly what makes you such.

 

[AssMan]

Is it possible to create a dohnut that's bigger than the earth?

 

[missAran]

Is it possible to create a dohnut that's bigger than the earth?

I wouldn't think so.

If God is all powerful can he create a rock that even he can't carry?

 

[NLB2]

NLB2: Because gravity is an effect on space, not simply an attraction between masses.

Ok, so then that stuff they taught me about Newton in physics class isn't true .

If God is all powerful can he create a rock that even he can't carry?

Omnipotence is limited by logic, therfore any hypothetical god would not have the power to make 4+3=5, a circle have four sides, or make a rock too big for that god to carry. Basically, a god cannot make change something that is neccesary a priori, whether it be analytic (such as a circle being round) or synthetic (such as 4+3=7).

 

[Hitokage]

Ok, so then that stuff they taught me about Newton in physics class isn't true

Kinda sorta. Newtonian physics still work fine for most everyday situations, but Einsteinian physics are simply more accurate as a model of the universe(keyword: more).

 

[NLB2]

Kinda sorta. Newtonian physics still work fine for most everyday situations, but Einsteinian physics are simply more accurate as a model of the universe(keyword: more).

So what's the cutoff between using Newtonian and Einsteninian physics? To shoot a missle towards Russia what model would be used?

 

[AntoneM]

to shoot a missle to Russia all that would be needed in Newtonian physics.

Assuming tachyons even exist, they exist, and only ever existed, in a state where they are are traveling faster than light in which case it's not a problem the problem lies in accelerating to or past the speed of light. this has to do with conservation of energy, and the fact that as an object, say a space ship, starts to approach the speed of light, the energy required increases exponentially to the point where if the ship wants to actually achieve light speed it would need infinite energy, this would hold true for anything that has mass. The theory is that Gravitons and Photons have no mass, that's why light and gravity both travel at the speed of light.

I hope that made sense.

 

[NLB2]

to shoot a missle to Russia all that would be needed in Newtonian physics.

Assuming tachyons even exist, they exist, and only ever existed, in a state where they are are traveling faster than light in which case it's not a problem the problem lies in accelerating to or past the speed of light. this has to do with conservation of energy, and the fact that as an object, say a space ship, starts to approach the speed of light, the energy required increases exponentially to the point where if the ship wants to actually achieve light speed it would need infinite energy, this would hold true for anything that has mass. The theory is that Gravitons and Photons have no mass, that's why light and gravity both travel at the speed of light.

I hope that made sense.

Gravity only travels at the speed of light? So if the sun suddenly dissapears, the earth will still orbit around it for eight minutes or so?

 

[AntoneM]

exactly

 

[Chrono]

I had this link bookmarked from an old gaf thread. Everybody should watch this (pretty long though -- 3 hours):

http://www.pbs.org/wgbh/nova/elegant/program.html

 

[Foreign Jackass]

you have any pictures of you with any of these girls you keep posting?

But then he'd have to prove he's really the guy on the pic. Let's face it, this is a dead end. And if he's really with that girl, just tell me what the hell he's doing here.

 

[Deleted member 4784]

IIRC, Einstein never said that we couldn't reach the speed of light; only that it would be an exceptionally difficult task to accomplish. For one thing, we already know from our tests on the tolerance thresholds of astronauts that at a certain point of speed/resistence, human beings will lose conciousness. Pushing a human being beyond this point is actually lethal. The problem isn't finding a means of reaching the speed of light so much as it is in finding a means for a human being's physiology to tolerate it. Then again, I'm not a physics major, so a lot of this stuff is waaay beyond my general scope of knowledge. :lol

 

[Dilbert]

Einstein never said that we couldn't reach the speed of light; only that it would be exceptionally difficult to accomplish. For one thing, we already know from our tests on the tolerance of astronauts that at a certain point of speed/resistence, human beings will lose conciousness. Pushing a human being past that point could be lethal. The problem isn't finding a means of reaching the speed of light so much as it is in finding a means of having a person survive it. Then again, I'm not physics major, so a lot of this stuff is waaay beyond my general scope of knowledge. :lol

Everything quoted is completely wrong.

 

[Deleted member 4784]

Do you mean to say that not only do human beings NOT have a recorded LD tolerance to resistence/speed, but I'm also a physics major?! Golly! :lol

Please be a little more specific if you're going to call me out on inaccuracy/ambiguity. Not that I don't doubt I'm wrong, but I'd like to know what exactly I'm wrong about...? As I said, I'm no physics major. LOL

 

[Dilbert]

Please be a little more specific if you're going to call me out on inaccuracy/ambiguity. Not that I don't doubt I'm wrong, but I'd like to know what exactly I'm wrong about...? As I said, I'm no physics major. LOL

We get it already: You're in Mensa, you're verbose, and you consider yourself to be pretty damn bright. But if you claim not to know anything about physics, then why are you weighing in on this topic?

 

[Deleted member 4784]

Hm I just looked it up and I seem to have misquoted Einstein. What he actually said was that you cannot accelerate from sublight speeds to light speeds and therefore the only way to reach the speed of light would be to already be at the speed of light. I think I got Einstein confused with Hawking or some other guy, since I remember reading some book saying that if you somehow warped spacetime around an object at rest then it would be possible to accelerate it at the point of light or something.

 

[Anthropic]

No, actually you were confusing G-forces with relativistic effects. You could accellerate to .999 lightspeed at 1G (which would take awhile) and never even notice that you were moving.

 

[Deleted member 4784]

We get it already: You're in Mensa, you're verbose, and you consider yourself to be pretty damn bright. But if you claim not to know anything about physics, then why are you weighing in on this topic?

Uh... Why are you getting so upset by my participation here? I never claimed to know anything about physics or bragged about being especially knowledgable on this or any other particular subject. I also don't ever recall bragging about being in Mensa or anything to that effect in my posts, so I must say that I'm a bit baffled as to how you would know that in the first place?

I'm just voicing my opinion here like everyone else has because this is an internet forum and that is what people do here. This is also a learning experience for me: I've now learned that my previous understanding of Einstein in this regard was wrong. That's the value of forums to me, is that they usually contain people far more knowledgable on a subject than myself. If I appeared condescending with my reply to you though, I'm genuinely sorrie, because I did not mean to give the impression of taking that tone with you. I only wanted to know what exactly it was about my statement that was incorrect so that I could go about correcting it.

Obviously, as verbose as I may be, I still am lacking in how to direct my questions to people since I seem to offend on a regular basis around here. Once again, I'm sorrie if I upset you. If it will make you feel any better about it, I will stop posting in this thread as I obviously have nothing to add to it in the first place.

 

[Hitokage]

Anyone moving at a constant velocity won't feel any different at any other constant velocity, be it 1mph or 20,000mph. What matters is acceleration.

 

[nitewulf]

Ok, so then that stuff they taught me about Newton in physics class isn't true .

classical mechanics (newtonian physics) does not work when you work with extremely fast objects (photons) and/or objects with infinitesimal mass (electrons). that's where quantum mechanics comes into play.
however classical mechanics holds for most objects we deal with in everyday life.

 

[Hitokage]

GPS systems need Relativity to work or the sattelite clocks would constantly go out of synch.

 

[nitewulf]

No, actually you were confusing G-forces with relativistic effects. You could accellerate to .999 lightspeed at 1G (which would take awhile) and never even notice that you were moving.

yes. you could accelarate much faster of course given well engineered support systems.
G-force on a mass inside a spaceship has nothing to do with reaching the speed of light itself.

 

[Hitokage]

G-force on a mass inside a spaceship has nothing to do with reaching the speed of light itself.

What is the crew supposed to be doing while their ship is accelerating to the speed of light?

 

[nitewulf]

GPS systems need Relativity to work or the sattelite clocks would constantly go out of synch.

well, relativity is actually a different model than quantum mechanics. einstein mostly worked with relativity, and didn't delve too deep within quantum mechanics, he did solve two unknown coefficients that deal with electron motion.

 

[nitewulf]

What is the crew supposed to be doing while their ship is accelerating to the speed of light?

that is a good question. i'm visualizing extremely slowed down metabolism within a jellolike substance, within some sort of a ceramic orb. the orbs themselves being supported by complicated control systems, that'll calculate stress, and move the orb around in small increments as necessary.
sci-fi basically.

 

[Saurus]

1. why is it that we can neve reach the speed of light?

Theoretically the speed of light could be surpassed by using wormholes...or something. I suggest you check out Michio Kaku's books. Awesome stuff.

 

[fallout]

Seriously guys, if you're in a university, try to audit the first half of a second year special rel. & modern class. Very interesting stuff and the only math is algebra anyway. Some horribly disgusting algebra at times, but at least it's not disgusting calculus.

 

[Phoenix]

Theoretically the speed of light could be surpassed by using wormholes...or something. I suggest you check out Michio Kaku's books. Awesome stuff.

Yes, but the speed of light cannot be achieved through conventional means. Wormholes and the like provide a mechanism to bypass the physical laws.

 

[Saurus]

Yes, but the speed of light cannot be achieved through conventional means. Wormholes and the like provide a mechanism to bypass the physical laws.

Exactly, kind of like a short cut.

 

[Dilbert]

Uh... Why are you getting so upset by my participation here?

Check your PMs.