Is this really true or it's just science fiction?

Aran · 03-29-2002

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.

**stevey** · 03-29-2002

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).

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.
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 !!!

**Shiro** · 03-29-2002

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.

**lightatdawn** · 03-29-2002

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?

**Shiro** · 03-29-2002

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.

**Procyon** · 03-29-2002

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.

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.

**shtarker** · 03-29-2002

>>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.

**Betazep** · 03-29-2002

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.

**Betazep** · 03-29-2002

>>>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?

**Betazep** · 03-29-2002

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)

**Betazep** · 03-29-2002

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.”

http://www.alphalink.com.au/~jdx/author.htm

If only this guy was a real scientist and had scientific proof... makes for an interesting argument though...

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.

LOL

**Nutshell** · 03-29-2002

Time is too abstract.

**lightatdawn** · 03-29-2002

>> 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:

Code:

unsigned infinitescope M = 0;
unsigned infinitescope E = 0;
do
{
     M = E + 1;
     E = M + 1;
}while (M < E)

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.

**Betazep** · 03-29-2002

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

http://www.newtonphysics.on.ca/faq/flat-universe.html

So could it be that the super atomic clocks are affected by velocity, kinetic energy, etc....? hmmmmmm

**Procyon** · 03-29-2002

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.

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.

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.

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 speed of light is actually about 300,000 km/s.

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.