Hi,
I have heard AND seen in movies that if you move at light speed or at least very very fast in space, and when u come back to earth, all other people will be much older than you do. Sounds scary.....is this true?
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Hi,
I have heard AND seen in movies that if you move at light speed or at least very very fast in space, and when u come back to earth, all other people will be much older than you do. Sounds scary.....is this true?
>I have heard AND seen in movies that if you move at light speed
>or at least very very fast in space, and when u come back to
>earth, all other people will be much older than you do.
This is known as the twin-paradox and not true.
No the twin paradox was that from the Earth's point of view you have aged less, but from your point of view the earth has aged less.
In reality if a person travels near the speed of light, they will age much slower then normal. So yes, planet of the apes (the original) is possible.
that movie is cool
i was just wondering that'll be pretty scary if you gone out to space and come back and find that everything u familiar wif is gone.....
As seeing as a guest of this board chose the username Einstein, now I have a question, do you think that he would be interested in Programming if he was alive?
I think he would want to know it, but wouldn't stick to it, he might use it as a tool to help him invent more things.
The reason for this is you can be in space and running around the earth at high speed but that dont mean anything because the earth will still spin at its normal speed it allways has done. So its like a basketball spinning on the floor and your running around it really fast. that doesnt means the basketball is going to spin faster too.:o So all im saying it the earth will still be normal but if the earth was spinning really fast then that is something totally different.
>No the twin paradox was that from the Earth's point of view you
>have aged less, but from your point of view the earth has aged
>less.
Yes, that was what Nutshell said.
If I climb into my rocket on earth and launch myself and approach the speed of light, fly some day around in space and return back, then from my point of view, the time on earth went faster. From earth's point of view, my time went slower. Or: from my point of view, my time went slower and from earth's point of view, their time went faster. It's just which position you take.
>In reality if a person travels near the speed of light, they will
>age much slower then normal. So yes, planet of the apes (the
>original) is possible.
Normal? In relativity there is no "normal", since everything is relative.
And in reality a person can't travel near the speed of light, since his/her mass would become infinite. If you use Lorenz transformation to calculate the new mass
m = m0 / sqrt (1 - v^2/c^2)
then you can see that if your speed approaches c, then
v^2/c^2
will approach 1, so
1 - v^2/c^2
will approach 0, and
sqrt (1 - ~1)
will also approach 0 and dividing by a very small number is the same as multiplication with a very large number, so m would become really, almost infinite.
This is the theoretical part. Now the practical part. If I want to accelerate, then I need energy to do this. The amount of energy which is needed to accelerate depends on the mass. If the mass is almost infinite, then also the amount of energy is infinite. By the way, energy should come from somewhere. As discussed in a different thread, mass can be turned into energy. So I need to carry mass with me to turn it into energy.....
[EDIT]
This is how I remember it from university. If things are incorrect, or new research resulted in new theories, please correct me.
[/EDIT]
>>then from my point of view, the time on earth went faster
No that is what the twins paradox is talking about. From the earth's frame of referance, the space ship is moving while they remain more or less stationary, causing the space ship to expirance time dilation.
However from the space ship's point of view it is the earth moving away from them, causing a time dialtion in the earth's frame of referance.
Relativity proves that both these observations are correct, thats where the paradox occurs.
physics and programming can go together, you know...
it is true according to Stephen Hawking and his book "a brief history of time". he's supposed to be one of the top brains arround, so it must be true !!!!Quote:
Originally posted by Nutshell
Hi,
I have heard AND seen in movies that if you move at light speed or at least very very fast in space, and when u come back to earth, all other people will be much older than you do. Sounds scary.....is this true?
his next book "universe in a nutshell" is also good i'd recommend it.
heres a poser, light travels at light speed(obviously), and so it must have no mass, or as stated its mass would be infinite at that speed.
so why does gravity affect light (it bends it), if it has no mass ?????
Its all relative:Quote:
heres a poser, light travels at light speed(obviously), and so it must have no mass, or as stated its mass would be infinite at that speed.
so why does gravity affect light (it bends it), if it has no mass ?????
http://math.ucr.edu/home/baez/physic...oton_mass.html
thats a good link, i had read that on the other thread you replied on.
doesn't quite explain it for me though.
in fact the fact that gravity bends light is a poser for far greater brains than ours, since light has no measurable mass it shouldn't be affected by gravity.
the common explanation is that mass bends the space-time continuum, ie the classic ball sat on a 2d sheet thing.
but thats beyond me frankly.:confused:
light is represented by a massless particle called a photon. Gravity will affect the partilce by altering its course, even though it has no mass (or relatively none).
I think we must differentiate between light and time. If you travel a billion light years from earth at a billion light years/unit, time will appear to stand still on earth whilst you age, although life is still going on at normal speed on earth.
i think current thinking is that photons are massless (even at the speed of light). if they had mass they couldn't travel at the speed of light.Quote:
Originally posted by Aran
light is represented by a massless particle called a photon. Gravity will affect the partilce by altering its course, even though it has no mass (or relatively none).
but gravity ONLY affects mass, therefore should not bend light.
thats why Hawking talks about mass distorting the "fabric of space" and thats a theory as to what gravity is.
and then i'm lost !!!
According to general relativity, gravity is the cause that space is bowed positive or negative, so it does not directly affect light, but light follows space and so it seems gravity is affecting the light.
Heres something to wrap your minds around; A question i posed to a friend only a few days ago... It would take an infinite amount of energy to accelerate any amount of mass to light speed since as its speed increases, the amount of energy required to increase it further would also increase, i'm sure you all know this... Anyhow, (hypothetically obviously) what would the result be of having an infinite amount of energy? ;)
I don't know, perhaps go faster than light? I remember reading that it is impossible for a subject to be at speed of light, but it seems not (theoretically) impossible to be faster than light.
Remember the Lorenz transformation for masses
m = m0 / sqrt (1 - v^2/c^2)
If v = c, then a division by 0 would occur. But what if v > c? Then the square root of a negative number would be taking, resulting in a complex number. Though I don't know what a complex mass would be, having a real mass and an imaginary mass perhaps?
Current motors use some kind of fuel to be able to work. If we need an infinite amount of energy, this would mean that we would need an infinte amount of fuel, that's impossible.
Satellites traveling through space make use of the energy of the planets. A satellite nears a planet, makes use of its gravity and then is lanched by that planet because gravity losses grip. Then the next planet does the same. I do not know how this really works, but I read about it in a paper that they used this mechanism to get satellites to Mars.
There's no paradox. In order to actually compare the times the twin has to turn around and go back to Earth, which means that you can't treat the two experiences as the same: when you use the time dilation equation you can define the Earth twin's frame as zero velocity throughout the whole period, but you can't do the same with the traveling twin because he has to accelerate mid-journey. So only one perspective is valid - that the traveling twin ages less.Quote:
Originally posted by shtarker No that is what the twins paradox is talking about. From the earth's frame of referance, the space ship is moving while they remain more or less stationary, causing the space ship to expirance time dilation.
However from the space ship's point of view it is the earth moving away from them, causing a time dialtion in the earth's frame of referance.
Relativity proves that both these observations are correct, thats where the paradox occurs.
>>I do not know how this really works, but I read about it in a paper that they used this mechanism to get satellites to Mars.
It’s called the sling shot effect and is actually an example of a perfectly elastic collision (one in which energy is conserved) so relativity has very little to do with it at all.
It helps to think of a simpler example, like a motor bike colliding with a semi trailer. When they collide the motor bike exerts a force on the semi trailer and the semi trailer exerts another force on the motor bike. Of course the force exerted by the semi trailer will be much larger than that from the motor bike and hence the motor bike will fly off in the opposite direction while the semi trailer will slow down a small amount.
A similar interaction occurs between the planet and space probe. The gravity from the space probe exerts a weak force on the planet while the planet’s gravity exerts a huge force on the space probe. The space probe gets spun round and shot out much faster in the opposite direction and the planet loses an insignificantly small amount of momentum.
And as to having an infinite amount of energy, I'm guessing that you would accelerate infinitely, causing you to go infinitely faster than the speed of light. However at that point as Shiro explaines, both time, your mass would first become infinite and your length 0. After that they all become functions of an imaginary number.
I may be a bit lost on this (never was real big into physics)... but if you travel away from the earth instantaneously at the speed of light for two years and instantaneously begin the return trip (so no acceleration comes into play) and it also takes you two years.... wouldn't that equal 4 years of time.
4 years of time equals 4 years of time, no matter how you put it. Distance isn't an issue....
So how could one person be younger or older? Four years of time passed no matter the speed of the earth's rotation, the speed of the traveller, or the size of the mole on his arse.
I think this is one area where science delves into speculation.
>>>If you travel a billion light years from earth at a billion light years/unit
Or how about a light second...
Light travels 300Km per second if I remember correctly. So in five seconds, a traveller leaving the earth (with instantaneous acceleration) at the speed of light would travel a distance of 1500Km in five seconds.
Bring him back to earth and give him a speed of five times the speed of light (1500Km per second) which is a speed of 5 light seconds/unit. So he moves in one seconds time to a distance of 1500Km which passes light fivefold. He returns at the same rate... and two seconds have passed. Two seconds for him... and two seconds for everything else in the universe.
Well?
Well I read the links.... guess it is real enough, but it still confuses me as to why. (Not so much so that I am going to change from programming to physics... lol)
http://www.alphalink.com.au/~jdx/author.htmQuote:
The book disputes Einstein’s time dilation concept and all so-called evidence supporting it. It re-establishes Newton’s absolute space-time, in which all motions can be accelerated or retarded, all physical objects can be bent or curved, but time cannot be dilated and space cannot be curved. By putting a first definition of time, it dismisses the myth associated with Einstein’s statement: “When an object moves, its time slows down.” No, it’s wrong. As long as an object moves in uniform motion, its time would never slow down. Time dilation only exists with those who cannot define what time is. If you know what time is, and that’s why Newton created absolute time, you would understand why the book dismisses completely Einstein’s time dilation concept which Kraus has described as “a major fallacy unique in scientific history.”
If only this guy was a real scientist and had scientific proof... makes for an interesting argument though...
LOLQuote:
Einstein said time is relative, and time can be dilated by motion. Newton said time is absolute and time can never change, but only motion can. The point is, if we want to say Einstein is right, first we must prove Newton is wrong about time. Has anyone ever proved Newton is wrong about time? My answer is no. All so-called evidence thought to confirm Einstein’s time dilation, in fact only confirm Newton’s law that all motions can be changed due to forces, but time is still absolute.
We both stand at a room’s corner with two clocks showing the same time. I move one clock to the other end of the room, then give it a really hard shake, then bring it back to check its time with your clock, and it shows 7 minutes slower. Based on my walking speed of 5 km/hr, Einstein’s equation predicts my moving clock would show (say) 2 seconds slower than your stationery clock. All physicists say the result is close enough, therefore they conclude time dilation has been experimentally proved: when an object moves steadily, its time slows down according to Einstein’s equation.
Now we repeat the same test again with my same movement inside the room at the same speed of 5 km/hr. But this time, not only I give the clock a harder shake, I even throw it to the ceiling fan, smash it many times on the floor, and bring it back, and it shows now 10 minutes faster (not slower). All physicists say, given of other factors, the result is still close enough, therefore they conclude time dilation has been experimentally proved: when an object moves steadily, its time slows down according to Einstein’s equation.
Time is too abstract.
>> However at that point as Shiro explaines, both time, your mass would first become infinite and your length 0
Exactly my point. If your mass is infinite then you will require an infinite more amount of energy.
Evaluate:
I dont see a clear answer. The only conclusion i could draw is that you cant actually technically achieve the speed of light even with an infinite amount of energy. You could however come infinitly close... nit picky i know but therein lies the fun. :)Code:unsigned infinitescope M = 0;
unsigned infinitescope E = 0;
do
{
M = E + 1;
E = M + 1;
}while (M < E)
http://www.newtonphysics.on.ca/faq/flat-universe.htmlQuote:
Does this mean that using common sense, (mass-energy conservation) we are led to abandon Einstein hypotheses? Is the universe simply mathematically flat? Therefore, all physical phenomena can be explained without space contraction and time dilation?
A - Yes. Certainly. All experiments and observations can be explained without Einstein's hypotheses. Einstein's hypotheses are useless. There are only three dimensions in space. All matter in the universe evolves in time, just as explained by Newton. Then, we can say that the universe is mathematically flat.
Let us recall that Einstein defines "Time" as what is shown on clocks. We have seen in the book: Einstein's Theory of Relativity versus Classical Mecanics (chapter two) that, due to mass-energy conservation, when potential or kinetic energies are absorbed by the particles (electrons) of the atoms, there is a real physical change of clock rate. Consequently, it is not acceptable to believe that "Time" really changes its rate, just because clocks run at a different rate. Using Newton's mechanics with the help of the de Broglie wavelengths of matter, we must examine all physics effects that can be explained realistically
So could it be that the super atomic clocks are affected by velocity, kinetic energy, etc....? hmmmmmm
Not at all; this is about as well-understood a phenomenon as there is. How exactly are you going to turn around without accelerating? If you're changing your direction of motion you're accelerating; acceleration is change in velocity, NOT change in speed.Quote:
Originally posted by Betazep
I may be a bit lost on this (never was real big into physics)... but if you travel away from the earth instantaneously at the speed of light for two years and instantaneously begin the return trip (so no acceleration comes into play) and it also takes you two years.... wouldn't that equal 4 years of time.
4 years of time equals 4 years of time, no matter how you put it. Distance isn't an issue....
So how could one person be younger or older? Four years of time passed no matter the speed of the earth's rotation, the speed of the traveller, or the size of the mole on his arse.
I think this is one area where science delves into speculation.
In any event, it's not like time dilation is just a wild unproven conjecture based on Einstein's postulates. It's quite easy to produce particles that travel at near light speed, and all their intrinsic processes appear to be slowed down. GPS satellites use relativity to maintain their accuracy. And dozens of other highly successful theories are structured on top of relativity.
The speed of light is actually about 300,000 km/s.Quote:
Light travels 300Km per second if I remember correctly. So in five seconds, a traveller leaving the earth (with instantaneous acceleration) at the speed of light would travel a distance of 1500Km in five seconds. Bring him back to earth and give him a speed of five times the speed of light (1500Km per second) which is a speed of 5 light seconds/unit. So he moves in one seconds time to a distance of 1500Km which passes light fivefold. He returns at the same rate... and two seconds have passed. Two seconds for him... and two seconds for everything else in the universe.
The calculation isn't that easy. In making relativistic calculations you have to specify whose reference frame we're talking about, and explain how this information is exchanged between reference frames.
Here's how you would go about this problem if you want to make the absolute minimum number of assumptions. Suppose the traveler is moving at a very fast speed, constantly emitting light pulses. Because he coveres distance between each pulse, the interval between received pulses (on the planet) is longer than the inverval of emitted pulses (on the spacecraft). Say this ratio is 3:2. The traveler emits a pulse every 10 minutes.
Pulse 1 emitted at 10 min, recieved at 15 min.
Pulse 2 emitted at 20 min, recieved at 30 min.
Pulse 3 emitted at 30 min, recieved at 45 min.
At this pulse the spacecraft turns around and heads back. Now, since he's heading back, the relationship inverts to become 2:3.*
Pulse 3 emitted at 30 min, recieved at 45 min.
Pulse 4 emitted at 40 min, recieved at 52 min.
Pulse 5 emitted at 50 min, recieved at 58 min.
Pulse 6 emitted at 60 min, recieved at 65 min.
And indeed there's a discrepancy. This is, of course, due to relativistic time dilation.
* This is not arbitrary. This inversion relationship has to be true if, for example, two rocket ships traveling next to each other should be able to exhange information in the same way as two stationary observers.
Yeah... like I said....
Then I posted a bunch of Newtonian thinking, not that I believe that relativity and time dilation isn't real... just for a contrasting point of view.Quote:
Well I read the links.... guess it is real enough,
would the time dilation effect still happen if a space ship were to enter a wormhole in our galaxy and appear in another galaxy (far far away) ??????
sci-fi i know, but wormholes do theoretically exist, and as i understand it you won't have actually travelled anywhere in the conventional sense.
so i was hoping time-dilation wouldnt occur, because lets face it, we live in a galaxy 100,000 light years across so even at light speed we can't travel very far, and when we come back there won't be anything we'd recognise.
so only a true WARP drive or wormhole is gonna get us anywhere at all !!!
Well such a drastic comparison couldn't be tested since at about(whatever) 300km per second, a space ship would have to be pretty damn far away for a light pulse to take 15 minutes to reach earth, and the pulse itself would be slowed and diffused as it passed through different media. SO accuracy wouldn't be so clean anyway, but you could probably rule out error factors...Quote:
Here's how you would go about this problem if you want to make the absolute minimum number of assumptions. Suppose the traveler is moving at a very fast speed, constantly emitting light pulses. Because he coveres distance between each pulse, the interval between received pulses (on the planet) is longer than the inverval of emitted pulses (on the spacecraft). Say this ratio is 3:2. The traveler emits a pulse every 10 minutes.
Pulse 1 emitted at 10 min, recieved at 15 min.
Pulse 2 emitted at 20 min, recieved at 30 min.
Pulse 3 emitted at 30 min, recieved at 45 min.
At this pulse the spacecraft turns around and heads back. Now, since he's heading back, the relationship inverts to become 2:3.*
Pulse 3 emitted at 30 min, recieved at 45 min.
Pulse 4 emitted at 40 min, recieved at 52 min.
Pulse 5 emitted at 50 min, recieved at 58 min.
Pulse 6 emitted at 60 min, recieved at 65 min.
And indeed there's a discrepancy. This is, of course, due to relativistic time dilation.
* This is not arbitrary. This inversion relationship has to be true if, for example, two rocket ships traveling next to each other should be able to exhange information in the same way as two stationary observers.
So that is theory based upon the theory (which I am not saying is wrong) that has other variables including the effects on the pulses themselves.... (sound has a doppler effect... do we know that light does not when we travel at high velocity?)
but I understand what you are saying. And you are right. Hey... Einstein is backing you.... :D
>>Exactly my point. If your mass is infinite then you will require an infinite more amount of energy.
But you have an infinite amount of energy. Even if there is infinitely more mass than there is energy, at infinity they are both the same amount.
>>sci-fi i know, but wormholes do theoretically exist, and as i understand it you won't have actually travelled anywhere in the conventional sense.
Last I head, some math genius went through the whole theory of worm holes and found some pretty big flaws, so I wouldn't really count of intergalactic warp drives any time soon.
well its debatable, but Stephen Hawking seemed to think they are theoretically possible, i read his book .also discusses warp drives. oddly enough he's a star trek buff. mebe weve both seen too much !!!!! :) beam me up Scotty !Quote:
Originally posted by shtarker
>>sci-fi i know, but wormholes do theoretically exist, and as i understand it you won't have actually travelled anywhere in the conventional sense.
Last I head, some math genius went through the whole theory of worm holes and found some pretty big flaws, so I wouldn't really count of intergalactic warp drives any time soon.
its far fetched, but it's a pity to discount the possibility, because i was thinking when reading this thread, getting a space ship to light speed isnt really possible, and that if we are to actually explore our galaxy (never mind another one), then even light speed is snails pace given the immense distances involved.
Actually, 15 light-minutes is only about the distance from Earth to the Sun and back. (And in any event outer space is too empty to affect the speed of light significantly.) And while the experiment I mentioned can obviously not be directly tested with current technology, many other relativistic effects can; I was just offering a hypothetical experiment to counter yours, which had a few flaws.Quote:
Originally posted by Betazep
Well such a drastic comparison couldn't be tested since at about(whatever) 300km per second, a space ship would have to be pretty damn far away for a light pulse to take 15 minutes to reach earth, and the pulse itself would be slowed and diffused as it passed through different media. SO accuracy wouldn't be so clean anyway, but you could probably rule out error factors...
Well, certainly, light has a Doppler effect. When in my experiment the ratio of emission to reception of the pulses was 3:2 that's nothing but a Doppler effect. But the Doppler effect doesn't change the speed of light. If these effects observed were medium-dependent (like sound) their nature would depend on our velocity through that medium, but many different lines of experiment say that's not the case; the speed and nature of propagation of light is the same no matter what your velocity is.Quote:
So that is theory based upon the theory (which I am not saying is wrong) that has other variables including the effects on the pulses themselves.... (sound has a doppler effect... do we know that light does not when we travel at high velocity?)
OK; That's good to know... but there are plenty of people around who will argue against anything, so one can never be too careful.Quote:
but I understand what you are saying. And you are right. Hey... Einstein is backing you.... :D
Consider this: (from popSci)
A person watches a time machine to see wheather a copy of himself emerges on, say, Tuesday. If it does not, on wednesday, he journeys back in time one day - emerging from the time machine on the same Tuesday when he had not emerged before. This can be reversed: If he does emerge on Tuesday, he simply waits until wednesday to choose not to go back in the time machine. In either case, a paradox is created: The time traveler is ther on Tuesday and not there at the same- a phenomenon that, intruigingly, echoes the same fundamental mysteries of particle behavior at the quantum level.
All of you should read this article not matter how much you believe you know at: http://www.popsci.com and while you're in the quantom leap: http://popsci.com's anti-matter article
So Betazep, you're going to believe an uneducated skeptic who is too arrogant to admit he cannot understand the math and science behind Relativity?
Special Relativity (the one that does not deal with accelerations and decelerations) is a fairly simple concept that, when properly explained, can be understood with a fair bit of ease. Mind you, it is relativity only in the sense that the absolute speed is that of light, and that light is always the same speed: it has nothing to do with spatial position. In fact, Special Relativity is mainly an extension of Galileo's Dictum - that we cannot sense velocity without an outside reference - to include the idea that we cannot sense velocity with some kind of light detector [compared with, for example, dropping a ball]. That light's speed remains constant to an observer while maintaining Galileo's dictum, time dilation is a necessary result. If, for example, a ship is moving and a beam of light is projected downward, to an outside observer it travels along the hypotenuse of a triange, so for a longer distance, than for the inside observer, who sees it travel straight down a leg of the triangle. Because the speed of light is constant to both observers, the observer inside the ship must have time pass less rapidly than for the outside observer viewing light moving farther, yet at the same speed, resulting in a greater time. If the beam of light were a ball instead, the speeds would be different, and nothing would be wrong with the differing perceptions of speed; hence, time only dilates because of light. That's the simple explanation that I have heard.
Of course, in science, truth is what works - if Relativity describes reality then it is of value: and it is certainly capable of describing time dilation with regards to GPS and other high-speed situations. Even if Relativity is not correct, it is handy.
There's not much math required to understand special relativity. Even performing calculations with relation to special relativity can be quite easy, at least in easy situations.
According to physics time does change depending on velocity.. i.e. when you leave earth.. But biologically your body will wear out at the same time as it was on earth... So as far as this discussion goes.. When you come back to earth you will find that your body is equally worn out as of others of your age.. But in terms of physics your age is different..
So you think that time doesn't have influence on the biological system? I think your body is a physical object which is ruled by laws of physics and therefore I think that if you reach high speeds (theoretically), your biological time is slowing down. The reason why we probably won't notice great changes it is that speeds which human bodies can reach are very low in relation to speed of light.
I think he meant that if you have spent the equivalent of seventy years in a space ship, your body will be that of a seventy something year old (depending on when you leave Earth); I don't think he means that people on Earth the thousands of years ago that you left it - in their timeframe - will have the same bodies.
No, this is completely incorrect. If this were true it would violate the whole premise of relativity in the first place. If the rate your body aged relative to the clocks nearby depended on your velocity, there would have to be an absolute standard of rest - the speed which caused biological systems to age most slowly relative to your clock. This would violate the postulates of relativity.Quote:
Originally posted by vasanth
According to physics time does change depending on velocity.. i.e. when you leave earth.. But biologically your body will wear out at the same time as it was on earth... So as far as this discussion goes.. When you come back to earth you will find that your body is equally worn out as of others of your age.. But in terms of physics your age is different..
I just odn't see why travelling at high speeds will be relative to the time. They are seperate things, also, time is abstract. You use time and speed to calculate the distance.
hmmm:
Speed= Dist. / Time
:D
thats what i said.
I dont mean to say that time remains constant.. To put it in your way.. I mean that Your body will disintegrate at a faster rate in space.. Which is if you return back will be the same as others.. Consider this
if you travel at the speed of light outside space.. In terms of physics time is slow for you.. But your body would disintegrate at a higher speed... When you return back the disintegration will be the same as that of others on earth
Is it possible to explain why time is slower if u travel at high speed in space?
Yes. . .well maby. . . .
I gave it a shot in this thread
http://www.cprogramming.com/cboard/s...threadid=14138
>>>So Betazep, you're going to believe an uneducated skeptic who is too arrogant to admit he cannot understand the math and science behind Relativity?
Nope. Any other questions?
>>>They are seperate things, also, time is abstract.
Well according to Netwton, time is a constant. That is how I have always believed time to be. When executions happen at regular intervals on my computer, it is because time is constant.
According to relativity, time is not constant when in motion.... so would my clock ticks be different when I am flying at 3/4 lightspeed? Well they would in reference to an identical computer that is at 0 mph...
When I run a mile, I may feel younger, but I never expected to actually be younger. If I ran everywhere for my entire life, I would sense less time than a person that lays around for their entire life. That is of course unless I ran against the spin of the earth, which would proposedly slow down my motion in space, and would make me age faster.
So it is all a bit obscure for me, but I still believe it to be true.
Time isn't a constant.... it isn't a measurement... it isn't accurate: especially when you are moving....
guess we all have to live with that...
perhaps a meter isn't a meter as well.... why should spacial distance be a constant when our defined 'time' isn't a constant...?
And maybe everything doesn't taste like chicken, maybe we are the chicken....
Next time you are late for work... tell your boss that time doesn't matter because you are late due to dilation!!!
What is one second
The SI unit of time(1 second) is equal to the duration of 9 192 631 770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the caesium-133 atom. Well consider that you wear a watch which works using the caesium 133 atom.
Now time in real sense will change when you travel at a higer speed(Speed of light).. But still the seconds ticking on the watch will be the same as on earth. Because the ocilation of the atom would be the same at any speed..
Sounds crazy when you think of relativity.. For example if you go out of the universe and watch the universe you will see the entire universe in different time frames... This theory is very usefull in complex calculations.. But note that there is nothink called the outside of the universe .. Everything is the universe.. Theory of relativity also works in the same fashion....
>I just odn't see why travelling at high speeds will be relative to
>the time. They are seperate things, also, time is abstract. You
>use time and speed to calculate the distance.
Not only high speeds, all speeds. But only when speeds are very high, you'll notice the effects of relativity. That's also the reason why classical mechanics (Galilei-Newton) works very well on earth situations. (Except physical experiments with high-energy and high-speed etc.) But the normal questions you'll get at school with moving cars, falling blocks etc. are well predicted by classical mechanics.
Classical mechanics is not false, relativity is just an addition to this theory.
Imagine your in a train which moves with speed V, as observed by an observer standing aside the railway. If a person in the train walks with speed U in the moving direction of the train, then you will measure the speed U. According to classical mechanics, the observer aside the railway will measure a speed W = V + U.
Now imagine that not a person is walking, but in the train someone turns a light on. A photon passes you with speed C (= speed of light). You will measure speed C. According to classical mechanics, the observer aside the railway will measure speed W = V + C!!
This is incorrect, photons travel with the speed of light which is a constant.
So speed is relative.
Imagine your in the train. You have a light at the bottom of the train and a mirror on the ceiling. If you put the light on, a photon travels to the ceiling and is returned by the mirror.
Assume the height of the train is H. Now the photon has travelled the distance 2 H. From your point of view.
But the train is moving. An observer aside the railway will measure a larger distance. Let me explain this with a simple graph:
L is the light, M is the mirror. At time = 0, the photon is launched. At time 1, it reaches the mirror. Note that the train has moved and to the observer aside the railway, also M has. M returns the photon at time 1. At time 2 the photon has returned.Code:
M M M
/ \
/ \
/ \
L L L
0 1 2
So distance is relative.
Here you can see that if you move, distances will look shorter for you than someone who is in (relative) rest. This is called length-contraction.
Since the speed of light is constant, the observer along the railway will say: "The distance is larger, the speed of light is constant, so the time will be longer."
So, for you travelling in the train, the time is going slower.
Hope I made it a little clearer.
Hope betazep get the point
I understood what you meant, and you're completely wrong. When you return to Earth after a long journey at a very high speed your body will have aged much less than the bodies of everyone left on Earth: it will age the same amount as everything else in your ship, including your mind. Everything that reliably measures time - your consciousness, a cesium-based clock, the aging process - has to remain synchronized according to relativity if they travel together. Your body's rate of aging cannot somehow become detached from your conscious mind's rate of aging.Quote:
Originally posted by vasanth
I dont mean to say that time remains constant.. To put it in your way.. I mean that Your body will disintegrate at a faster rate in space.. Which is if you return back will be the same as others.. Consider this
if you travel at the speed of light outside space.. In terms of physics time is slow for you.. But your body would disintegrate at a higher speed... When you return back the disintegration will be the same as that of others on earth
It is just that you guys dont understand the thory well... it is just that you are all watching a lot of sci fic movies... The theory means calculates time according to the speed you are travelling in.. In space there is no fixed point.... To make calculations easier you have to consider something as fixed.. but everything is in motion. So you use the theory of relativity to calculate the speed of light emited from planets etc..
Time , distance and spee d are three entire different entities.. That dosent mean that if you travel at the speed of light time will decrease...
Time is not constant.
(There is no way eight hours at work is the same as eight hours at play.....)
If I managed to get close to the speed of light and my mass increased. Would the mass of fuel I have also increase?
Thus the energy derived from the fuel increase proportionally to the energy needed to propel the ship?
Not this:- When you are on different planets your mass id diffeent.. SO mass depends on gravity... And also note this energy can be neither created nor be destroyed.. So all your hyposis are wrong...
>>When you are on different planets your mass id diffeent.. SO mass depends on gravity... And also note this energy can be neither created nor be destroyed..
Then e=mc^2 is not correct. As mass changes but energy can not. (provided the speed of light is independant of gravity)
>>SO mass depends on gravity
I thought
mass*accel = weight
(accel==gravity most of the time) but mass was constant even if weight changed.
A mole of petrol made at Earth standard gravity would produce more, less or same energy than one made at half Earth standard gravity.
What would happen to the mole of petrol if you took it between differing gravities? ie earth to moon? Would the energy output change?
>> What would happen to the mole of petrol if you took it between differing gravities? ie earth to moon? Would the energy output change?
No.
In this case the energy derived is through breaking chemical bonds between atoms. A mole of petrol will always have a set number of molecules and therefore a set number of bonds to break.
Chemistry is soo much easier.
E=mc^2 is not Einsteins equation.
The equation derived is E^2 = (mc^2)^2 + (pc)^2
If the observer and the object are in the same frame of reference (FoR) and both are stationary relative to each other then p=0, and the equation simplifies to the ever famous E=mc^2 (the negative solution be mathematically valid but physically unreal) which is the one generally used to calcuate things such as energy released in nuclear reactions since everthing is in same FoR and generally isn't moving anywhere.
More later if I can find my physics degree notes and textbooks on this subject (I think they may be unaccessable and at my parents house though).
As for Newtonian mechanics and particularly the kinetic energy of an object being 0.5*mv^2. This is the 1st order approximation of the above if you use the lorentz transform to substitute for the momentum and then one of the mathematical expansions to expand the series (I forget which one).
Newtons 3rd law and conversation of momentum and energy still apply for Trucks hitting bikes, bikes are worse off, they have less mass. Its only a simultaneous equation and can be reasonably approximate for the sake of why the biker dies as a perfectly elastic collision with solid non-deformable structures.
To be really confused consider electric and magnetic fields and how they change in different relativistic frames of reference.
One of the early experiments to prove that time dilation did, in fact, occur was observing the half life for the decay of muons. Low energy muons poduced on Earth decayed at the expected rate, but high energy muons arriving from cosmic rays travelled a lot further, indicating that time was running slower for them.
Your mass doesn't change no matter where u are, it's 'WEIGHT" that changes due to gravity.
You forgot to add "Your inertial mass only changes due to how fast you're moving relative to a stationary frame of reference"Quote:
Originally posted by Nutshell
Your mass doesn't change no matter where u are, it's 'WEIGHT" that changes due to gravity.
I also vaguely recall helping to explain this before, can't remember if it was these boards or the old ones though.
>Then e=mc^2 is not correct. As mass changes but energy can
>not. (provided the speed of light is independant of gravity)
Also energy can change. Note that also in classical mechanics that's a fact. If you take a stone and put it at some height, it has a certain amount of energy. If you take the stone heigher, it's energy increases.
Matter and energy are two faces of the same thing, they can interchange. Think of matter as frozen energy.
That's essentially correct, at least as seen from the perspective of a nonaccelerating observer. Someone on Earth would notice that as your spaceship picks up mass it becomes more and more difficult to accelerate itself, and the rate of acceleration of the ship will drop as the ship approaches light speed.Quote:
Originally posted by novacain
If I managed to get close to the speed of light and my mass increased. Would the mass of fuel I have also increase?
Thus the energy derived from the fuel increase proportionally to the energy needed to propel the ship?
(Actually, this only applies if you're being accelerated by an external energy source. For a ship carrying its own fuel there should be no difference; all the kinetic energy you acquire has to have been found inside the fuel originally.)
You'll see something quite different on the ship, though - you don't detect any increase in mass of your ship. However, as you approach light speed, the universe around you will seem to compress along the direction in which you're moving, allowing you to reach any destination easily within your lifetime if you can provide enough energy.
Well saying they'll be really old isn't accurate. It slows down time as you experience it. It's all in Einsteins theory of relativity. Just a relativity question: It is theoretically impossible to move faster than light. RElative to what? If two rays of light pass eachother, relative too the other one, the first will be travelling at 332,000 miles per second (600,000 km / second) - twice the speed of light. Is that a relativity loophole?
>>Shiro: Also energy can change.
We were refering to the laws of themodynamics.
That is;
Energy in a system remains constant. It can not be created or destroyed and tends towards more random states.
but
if your mass increases as you approach the speed of light, does this not increase the available energy? (as available energy is mc^2)
>>shtaker: the energy derived is through breaking chemical bonds between atoms.
Doesn't the pressure and temprature at which a chemical reaction take place influence the energy output? (or only the speed of the reaction?)
I thought if the 'petrol' was on a planet with, say twice the gravity, the chemical bonds would have to be much stronger to form the 'petrol', thus releasing more when broken.
<useless nitpicking>Quote:
>>Shiro: Also energy can change.
We were refering to the laws of themodynamics.
That is;
Energy in a system remains constant. It can not be created or destroyed and tends towards more random states.
but
if your mass increases as you approach the speed of light, does this not increase the available energy? (as available energy is mc^2)
The first law of thermodynamics is actually just a clarification of the law of the conservation of energy and really only applies to heat.
</useless nitpicking>
However the mass increase and extra energy associated with it comes from the energy released burning the fuel powering the rocket.
No.Quote:
>>shtaker: the energy derived is through breaking chemical bonds between atoms.
Doesn't the pressure and temprature at which a chemical reaction take place influence the energy output? (or only the speed of the reaction?)
I thought if the 'petrol' was on a planet with, say twice the gravity, the chemical bonds would have to be much stronger to form the 'petrol', thus releasing more when broken.
The energy is derived from the petrol reacting with oxygen.
The principal behind this is relativly easy, energy is required to break a bond, while energy is used to form bonds.
A pratical example of this is disolving table salt in water. Sodium chloride is ionicly bonded (this is the most simple chemical bond between a metal and a non metal, where an electron is taken from the non-metal and given to the metal. They then have opposite charges so stick together) which means it has no real molecules, only a large ionic lattice. Therefore to dissolve it in water the strong ionic bonds holding this lattice together must be broken and replaced be much weaker bonds between sodium ions, chloride ions and water. As much more energy is required to pull the sodium and chloride ions apart, the energy to do so is taken from the water in the form of heat, hence adding as little as a teaspoon of salt to a cup of water can cause a drop in temprature of up to 5 degreease.
Temprature and pressure have nothing to do with the energy given off, they will just alter the rate.
And as for the rate alterting the energy out put, the number of atoms, and hence the amount of chemical energy stored in each bond, does not change no matter how fast the things react.
Finally gravity has no effect on the strength of the bonds. The strength is detirmined purely by the type of bond and the electronegativity of the atoms involved.
So that petrol station on the moon is not as good idea as I thought.
shtaker:The first law of thermodynamics is actually just a clarification of the law of the conservation of energy and really only applies to heat.
And strangely money. As the world bank uses the laws of thermodynamics, applying them to world markets.
(unfortunately you can add more money to teh system by minting it)
>>> Is that a relativity loophole?
No.
Relative to a hypothetical observer on one or other of the beams the other beam will be approaching at the speed of light.
Relative to a stationary observer, both beams will travel at the speed of light. If the beams are in opposite directions, then the effective speed at which they are approaching each other will be faster than light, but, and it's a big but, the speed at which they are approaching each other is an abstract concept, nothing physical is actually travelling faster than c.
>>And strangely money. As the world bank uses the laws of thermodynamics, applying them to world markets.
(unfortunately you can add more money to teh system by minting it)
No wonder I'm still poor, I've been looking at it in completly the wrong way
But I do remember reading some where about about a person (probbaby a really bored accountant) who worked through and tried to solve all the economic formulas and what not.
The end result, 1 = -1.
>>> The end result, 1 = -1.
A little limiting of course, a statistian would be a better bet...
1 = "What do you want it to equal?"
Having just read 4 pages of formula and confidence inspiring theory - what if we don't know enough yet to be correct?
Imagine that we were discussing manned flight about a 2000 years ago.
most theories would say that you would have to act just like a bird .. be light and flap wings in proportion to the weight being carried - and it would make sense.
now we know that its all to do with air pressure differences - something nobody knew about even 300 years ago.
My point being that although we have a number of theories that either say yes, warp speed is possible, or no it isn't - it is really only guessing.
Looking back at the time of the romans and putting todays knowledge into practice - they could have easily built an aeroplane with their technology.
"My point being that although we have a number of theories that either say yes, warp speed is possible, or no it isn't - it is really only guessing"
Hardly guessing, relativety has been "proved" umpteen times.
No-one will ever travel faster than C in linear space. Never gonna happen.
However, theoretically there are other possibilities:
Wormholes, could possibly provide a way to travel great distances in small lengths of time.
"Warping" ala Star Trek offered a possible way round the speed of light limitation................... unfortunately it turns out that in order to "warp" space you need 10x more energy than there is in the universe..... bummer.
"The first law of thermodynamics is actually just a clarification of the law of the conservation of energy and really only applies to heat"
Since when? It applies to ALL forms of energy, not just heat: potential, kinetic, etc.
>>Since when? It applies to ALL forms of energy, not just heat: potential, kinetic, etc
That is the law of conservation of energy. It simply states that energy can neither be created or destroyed. The first law of thermodynamics is similar but says that when something changes state it will usually do so as a response to external energy flows. Energy may be supplyed as such:
1: Heat energy (joules) flowing into the system.
2: Work done on the system (such as compression from an external force).
Hence the law of thermodynamics is a clarification of the law of conservation of energy.
>>> what if we don't know enough yet to be correct?
This is, of course, correct. However, to get to a more advanced state, one has to begin somewhere, and where we are now, is where we are. The flight analogy is not a good one to use though, sure planes do not work entirely like birds, but birds are heavier than air, (you can weigh one if you like), and they do fly - fact, heavier than air flight is possible. Back then, they knew this, they simply did not know how too.
We do not have an observation of faster than light travel, so at this point, we do not know that it is possible.
>>> Hardly guessing, relativety has been "proved" umpteen times.
A little devils advocating here, but, nothing yet has conclusively proved relativity to be wrong, not quite the same thing. There have been some counter claims, but at the moment, the big money is in the standard model, so to protect budgets, departments and careers, people like to stay in there. I'm afraid things will be like that while research grants are allocated in the way they are today.
>>> Never gonna happen.
Horribly long time, never!
Hmm, i cant find a link to the article now but if its true you can look at www.space.com . NASA had contracted some company to construct a device that can successfuly reduce the effects of gravity. Well if this is true and it can be refined to eliminate gravity's effects than light speed travel would be feasable since with out gravity you dont have no mass!