Since the Earth and Mars orbit the sun at different rates (they do, right?) wouldn't an astronaut that goes to Mars encounter some of the strange relativistic effects of being there? Like when they got back wouldn't less time have passed for them then for us?

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They would have aged at different rates but the variation in the space time is only a fraction compared to the variation in time at things traveling at near light speeds, mars and our fastest spaceship travels nowhere near a fraction of the speed of light

Their atomic clocks will tick a little faster on Mars than on the earth, but they won’t notice any biological age difference. Anyway, humans go by thermodynamic time, not atomic time. I assume they will be in nice warm space suits while on Mars. The orbit speed around the sun doesn’t have anything to do with this.

Yes, they do orbit at different rates. The relativity part, there would be no noticeable difference for the astronaut. Relativisitic effects (worth mentioning anyway) are only at VERY high speeds, otherwise you would technically be aging more slowly if you were running past someone!

The relativistic "time factor" is a function of (1 - v^2/c^2).

A "back of the envelope calculation gives a relativistic "time factor" of approximately 2 parts in a billion between Earth and Mars. Your watch would gain about 1 second every 15 years. Not exactly worrisome. Besides, the GR effects of the differences in gravitational potential would probably swamp the SR effects for velocity differences.

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Err, not exactly; you mean its a function of the square root (1 - v^2/c^2).
:wink:

G^2

#-o Dang! ops:

That would make the correction factor 1 part in a billion or about 1 second every 30 years.

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By the way, it may be of interest here to realize that:
Velocity time dilation becomes equivalent to GR gravitational time dilation when the particle's velocity is equal to the escape velocity at that location.

G^2 8)

[Johnny Carson voice] I-I-I did not know that. [/Johnny Carson voice]

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I see, so how fast abouts would you have to be moving before you noticed any difference?

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Note to Kebsis: Sam5's views do not represent the prevailing view of the scientific community. Depends what you mean by "noticed." For an atomic clock, just going into orbit produces noticeable time dilation. To notice on a wristwatch, you'd need a decent fraction of the speed (10%? 30%? not really sure though) of light for a while few months. To notice in terms of biology, ie. going on a 2 year trip and coming back to find your newborn baby is a teenager, that would require a high fraction - more than 90% for those two years (your time).

Maybe someone else can quantify it better for you though.

Note to Kebsis, this is a myth:

The kid is moving relative to you and you are moving relative to the kid, this causes the “clock paradox” of the 1905 SR theory, which Einstein finally realized was wrong and he corrected it in his 1918 paper by adding accelerative effects, gravity fields, and atomic clocks. Humans can’t accelerate fast enough to notice a biological time difference, because such a large amount of acceleration would crush them first.

For information about "thermodynamic time in biology", look it up on Google. Many scientists explain it in their papers.

Acceleration is not the issue, velocity is. But humans are unlikely to be able to achieve velocities where relativistic effects can be easily detected.

No it is not !

As you have been told many times, in many threads, by many people;
GR is not a correction of errors in SR. It is an extension from the special conditions of SR to the general conditions of GR

Yeah, right! An acceleration of one gravity for one year would suffice to reach a significant fraction of the speed of light. Certainly enough for time dilation to be noticeable.

Yes, please do. And you will find that Sam5 does not understand it any better than he understands relativity.
What he said!

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If we accelerate something at 9.8 m/s/s for one year, it will attain light speed near the end of the year. That's a result of there being about 30 million seconds in a year, so after a year, the velocity would be 300 million m/s--or, 300,000 km/s, more familiarly.

But an object that experiences such an acceleration will not experience a constant g, because of the distortion of its spacetime. How would that work? At one half c, gamma is what? 1/0.866? About 1.15 right? What does that do to our 9.8 m/s/s? Their rulers are shortened, so our meters are much longer, to them. Our seconds are shorter than their seconds, so the acceleration that they'd experience would be times 1.15 cubed, right? 1.5 g?

Simple out: Assume the 9.8 m/s^2 is measured on your ship, or the constant output of its drive. That'll avoid the squishing of passengers, and makes it much more reasonable to explain as a drive behaviour. But then, instead, you get into the issue of what happens at the end of the year, as measured by those on board....

Meanwhile, though, what will happen is that those outside the ship, and at rest relative to its origin, will see the ship's acceleration being reduced, as it creeps up on c.

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Exactly. It never gets to c. So that's not so simple an out as it might appear.

The flaw in K’s logic is when he considers the earth to be the only “stationary” object in the universe, and when he measures the “speeds” of all objects relative only to the earth. This is a geocentric point of view, which Galileo did away with 500 years ago.

The moving rocket is moving not only relative to the earth but relative to everything else, and so we can't decide on the absolute atomic oscillation rates of the rocket and its passengers, based only on its motion speed relative to the earth, since, relative to some other objects, the rocket is not “moving” relatively at all. For example, if the rocket is moving away from the earth at 90% of the speed of light, in the direction of a galaxy that is ALSO moving away from the earth at 90% of the speed of light, then the rocket is NOT MOVING relative to the galaxy. Therefore, no one can’t say that the absolute atomic oscillation rates of the atoms in the rocket “slow down” a lot, due to the motion of the rocket relative to the earth, but not at all, due to the motion of the rocket relative to the galaxy. There can be only one absolute oscillation rate of the atoms in the rocket.

The “speed limit” was invented by Lorentz, not Einstein, and it was related to the “resistance” to the motion of a mass put up by a field through which the mass was moving.

And then, of course, there are the earth-relative “superluminal” galaxies, which are traveling at more than “c”, relative to the earth, and we are traveling at more than “c”, relative to them.

So far as I can tell, you're the only one here who posits anything like a preferred reference frame.
Assuming everyone involved is in an inertial reference frame and is measuring when the rocket passes by them (so we don't get any annoying doppler effects) then there is a maximum oscillation rate (that measured by observers in the same reference frame as the rocket). Everyone else measures a lower oscillation rate.

This has been discussed ad nauseum in perhaps half a dozen other threads; there is no point in doing so again. Sam5 seems incapable of either doing the math or believing the results.

You have no “results”. You have only fantasy theory.

An illusion of a Doppler shift is called the Doppler Effect, discovered by Doppler in 1842.

The first part of this discussion was about the “real” time of moving objects, not the illusion caused by a Doppler effect.

A real object can not be an infinite number of “real” ages, based on who is “looking” at it at the moment. You need to understand the difference between a real clock rate and an illusional clock rate. Relative motion and the Doppler Effect causes an illusional clock rate to be “seen” by observers, but a “real” clock rate is only one real rate, at the clock in question, and this is not altered by “relative motion”. It is only altered by a real physical force being placed on or experienced by the clock. Just “relative motion” does not cause such a real force to be placed on the clock.

An atomic clock slows down in a strong gravity field, and it speeds up in a weak one, due to the two different gravitational forces placed on the clock. This also happens with the acceleration of an atomic clock. But it does not happen due only to “relative motion”.

This is why Einstein added the acceleration and the gravity field to his SR theory in 1918, and this is why he didn't use just "relative motion" in his 1918 version of the SR theory. You need to study more of his actual papers and read fewer of the pop-science books of today.

Sam5, we've been here before, you've already had at least one thread locked on the subject. I'm willing to discuss the subject, but not with you.

It doesn't matter how fast you are moving, you still would not notice any difference, at least not according to your own clocks moving with you on Mars. You need to be able to observe the clocks on earth while you are located on Mars (or after returning from Mars) in order to see a difference. Then it is simply a matter of clock accuracy as to whether or not you will be able to 'notice any difference'.

In the previous discussion of time dilation, Kaptain K and I, for example, were making an implicit assumption (required by SR & GR) that one is able to observe & compare clocks in two different frames.

G^2

I did not!
The rocket accelerates relative to the Earth and is, there for a non-inertial frame of reference. The symetry is broken and the direction of the time dilation is unambiguous.
A "fantasy theory" that is shared by 99% of phusicists who can actually understand the theories of Relativity (i.e. The math, not just the thought experiments that Sam5 loves to pick at, thinking he has "disproved" them.)

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Surely this violates the Principle of Equivalence? The crew of such a spacecraft should feel precisely the same effects as the crew of a motionless spacecraft sitting in a homogeneous gravitational field of 1g - viz a constant g. No?

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When they start, that would seem to be true. The clue to the eventual difference is that they can never get to c. That's not a paradox, just a result.

Otherwise, as the good Kaptian said, it'd only take a year at an acceleration of g to get up to c.

There is no difference, Sam5, so try to cut back on the pseudoscientific crap. [-X

The difference in the passage of time between Earth and Mars would be a matter of microseconds per year, because of their different positions in Mars', Earth's and the Sun's gravitational field, as well as the difference in the radius of Earth and Mars, leading to a different acceleration.

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Nope. K's view of the laws of physics is the same as anyone else. That is Postulate 1 from Special Relativity.

Wrong. We can measure, in principle, the time dilation between two clocks which are in relative motion.

So they are comoving.


Since there are no absolute times we cannot say that there is such a concept of "absolute atomic oscillation". So wrong again.

Furthermore, Einstein estaablished that the rate at which a clock "ticks" is dependent on its position in a gravitational field, so although the clock maybe comoving with the galaxy, its clock rate will be different since it is not in the same position in the gravitational field, as the galaxy.

There can be only one absolute reply: WRONG!

WRONG!
WRONG! If Lorentz assumed an ether, he did not predict time dilation because of movement through an Ether. Einstein showed that the concept of a stationary ether that produced a Newtonian absolute frame of reference was unnecessary and inconsistent with Maxwell's Electrodynamics. Don't you read ANYTHING?

...a result of geometry and doppler delay and nothing more. No object actually travels at or greater than c in any frame of reference.

Sheesh. Five wrong and the thread is yet young....

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The crew of the accelerated spacecraft may feel that they were accelerating at 9.8 m/sec**2, the outside observer would see the acceleration taper off, asymptotically approaching zero as the spaceship approaches c.

Jeez, and I thought we were done with all of this!

So you agree with me, and you disagree with milli? To an outside observer the acceleration is constantly decaying, but to those on board it's just constant.

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