Acceleration/Deceleration

[rigney]

Because we know the theory, and we let smart people work on the projects.

 

 

Should I take that as a posture of ambivalence, or do you even relate to what I said? And you really should holster that thing you're waving around, it could be frightening to some folks.

[swansont]

Perhaps I misunderstood your question. I read it as "How is it that we have this thing called relativity and yet all the projects seem to work?" We know the theory and how to apply it. The specifics of the application will depend on a specific mission.

 

Were you asking something else? Or do you have a particular example in mind?

[rigney]

Perhaps I misunderstood your question. I read it as "How is it that we have this thing called relativity and yet all the projects seem to work?" We know the theory and how to apply it. The specifics of the application will depend on a specific mission.

 

Were you asking something else? Or do you have a particular example in mind?

 

 

If you reread my question I think you'll understand. I worked in missiles for several years. Ft. Bliss, White Sands and McGregor Range was my second home. No!, better yet; let me say: my first home. As Platoon Sgt. of a Launching Area, the intricacies of getting a missile, or missles ready for a firing was more than just mechanics, but nothing compared to the guys working in the I.F.C. (integrated fire contol). What we had at our disposal at the time was nothing compared to what these guys contend with today. My question was and still is, how is the compilation of data intergrated, to compensate for the speeding "up or slowing" of these machines moving at such fantastic speeds?

[Cap'n Refsmmat]

Fortunately, manmade craft don't travel fast enough to get significant relativistic effects -- there's no huge time dilation on the way to Mars, for example.

 

GPS satellites have to manage time dilation, but they simply use a formula to correct their clocks, and they don't have to do fancy maneuvers or guidance in orbit.

[Moontanman]

You are at odds with actual experiments. This is not some hypothetical musing or dorm-room conjecture. If you move clocks, their rates change. When you compare them to clocks that did not move, they read out different times. When you put clocks in a different gravitational potential, it ticks at a different rate.

 

None of this depends on the specific type of clock. It's not a mechanical effect — the clocks are not broken on some way.

 

I understand it is not a mechanical effect swansont, I understand it can be measured, I also understand that time slow down is not real from the stand point of the moving guy as he observes the universe from inside his craft. His time actually slows down, he survives the trip to Andromeda, the people he left behind age at the regular rate, they will be millions of years dead even though the universe looked time dilated to the astronaut.

[swansont]

Fortunately, manmade craft don't travel fast enough to get significant relativistic effects -- there's no huge time dilation on the way to Mars, for example.

 

GPS satellites have to manage time dilation, but they simply use a formula to correct their clocks, and they don't have to do fancy maneuvers or guidance in orbit.

 

However, they do compensate for effects like the doppler shift. The band width of the signals can be fairly narrow, and one needs to know what frequency to either detect or send in order to communicate. But that's simple dependent on speed, and can be easily compensated for. It's one reason why a GPS receiver takes longer to lock on to a satellite signal when its downtime is increased — the clock is out of sync, and it has to scan frequencies instead of "knowing" where a satellite is and what frequency (and frequency shift) to use.

 

But that's all in software — no user action is required. Because we know the theory, and smart people built the system.

[rigney]

I know!, it would cost a few bucks extra to get it done, but you'd think they'd put those GSPs units in a (+ or - 0), geosynchronous tiaxial orbit where they wouldn't need the software to compensate for red shift, doppler, columnation, or etc.? And I firmly believed down time to a satellite shouldn't be fooled around with other than getting it started or stopped.

Edited July 2, 2010 by rigney

[insane_alien]

I know it would cost a few bucks extra to get it done, but you'd think they'd put those GSPs units in a (+ or -), 0 triaxial geosynchronous orbit where they wouldn't need the software to compensate for red shift, doppler shift, columnation, etc. might be a good idea?

 

they'd still need it

 

triaxial? then its not geosynchronous.

 

the accuracy would be terrible from that distance.

[Cap'n Refsmmat]

It'd also be more difficult to get a strong signal from geosynchronous orbit. That's quite a distance.

[J.C.MacSwell]

I know it would cost a few bucks extra to get 'er done, but you'd think they'd put those GSPs units in a "0" triaxial geosynchronous orbit where they wouldn't need the software to compensate for red shift, doppler shift, columnation, etc. might even be a good idea?

 

If it's geosynchronous it's fixed to (one particular of) Earth's reference frame... however this is not an inertial frame, and clocks on it will disagree over time if left alone uncorrected.

[rigney]

If it's geosynchronous it's fixed to (one particular of) Earth's reference frame... however this is not an inertial frame, and clocks on it will disagree over time if left alone uncorrected.

 

 

I actually thought an inertial, geosynchronous and (geocentric) point were on the same reference line. Well, I may eventually get it right!! Thanks

Edited July 2, 2010 by rigney

[swansont]

It'd also be more difficult to get a strong signal from geosynchronous orbit. That's quite a distance.

 

They are about halfway to geosynchronous. Coverage becomes an issue, not because of the power, but because of the equatorial orbit not giving a good signal to higher latitudes.

 

The precursors to GPS investigated several of the options (Transit, to support Polaris submarines, SECOR, 621B and TIMATION), and each had at least one drawback. GPS was a compromise that blended good features and minimized limitations.

 

http://blogs.scienceforums.net/swansont/archives/5588

[D H]

And all thousands observers will all measure different deformations of one single undeformed reality.

That "one single undeformed reality" doesn't exist. It is those measurements that are real -- and yes, they sometimes are apparently contradictory. So be it. That is the universe in which we live.

[michel123456]

Amazing.

I say:

Reality is one.

 

Or do you disagree even on this simple statement?

[swansont]

Amazing.

I say:

Reality is one.

 

Or do you disagree even on this simple statement?

 

I don't know what "reality is one" means.

[michel123456]

Unique.

 

------------

 

The question was addressed to DH.

[rigney]

If we can, I'd like to get back to the original question of time dilation. Suppose our ability to travel at C: is finally achieved and we can sling something out into space at that speed, other than photons,(a light beam)? As I'm beginning to understand it, at C; an atom simply stops working, or at best, is barely moving and its kinetic energy goes to maximum. What have we proven, other than that a machine as such might not rust or decay during the trip? But what would happen to humans on board without cryogenics or some sort of suspended animation to protect them as a cyborg? We are not machines, nor inanimate and without such a process, our bodies would be almost instantly dead. Even if it could actually withstand that speed, at C the normal aging process in a human would not stop. Unless we find a method to retard this process, even on a short trip to Alpfa Centauri and back, your space ship might look nine years less older, but not you.

Edited July 5, 2010 by rigney

[swansont]

If we can, I'd like to get back to the original question of time dilation. Suppose our ability to travel at C: is finally achieved and we can sling something out into space at that speed, other than photons,(a light beam)? As I'm beginning to understand it, at C; an atom simply stops working, or at best, is barely moving and its kinetic energy goes to maximum. What have we proven, other than that a machine as such might not rust or decay during the trip? But what would happen to humans on board without cryogenics or some sort of suspended animation to protect them as a cyborg? We are not machines, nor inanimate and without such a process, our bodies would be almost instantly dead. Even if it could actually withstand that speed, at C the normal aging process in a human would not stop. Unless we find a method to retard this process, even on a short trip to Alpfa Centauri and back, your space ship might look nine years less older, but not you.

 

Atoms will not stop working at speed approaches c

There is no limitation on the human body of traveling at any speed; we are traveling at such speeds with respect to cosmic ray protons right now. The problem would be in dealing with the acceleration.

Humans would not age at a different rate than anything else in the reference frame. If the trip took 10 years in the spaceship frame, the humans would age 10 years.

[Moontanman]

Atoms will not stop working at speed approaches c

There is no limitation on the human body of traveling at any speed; we are traveling at such speeds with respect to cosmic ray protons right now. The problem would be in dealing with the acceleration.

Humans would not age at a different rate than anything else in the reference frame. If the trip took 10 years in the spaceship frame, the humans would age 10 years.

 

Yes, but in ten years at very close to C you could travel hundreds if not thousands of light years, to you the rest of the universe looks time dilated to them you do... which is real after you come back to you starting point? You have aged ten years they have aged thousands of years yet to you when you were traveling they looked as time dilated to you as you did to them but once the trip is over only your time dilation is real.

[rigney]

Atoms will not stop working at speed approaches c

There is no limitation on the human body of traveling at any speed; we are traveling at such speeds with respect to cosmic ray protons right now. The problem would be in dealing with the acceleration.

Humans would not age at a different rate than anything else in the reference frame. If the trip took 10 years in the spaceship frame, the humans would age 10 years.

 

 

Only trying to look at it conjecturally, but isn't atrophy our biggest problem with space flights at this time? And does anyone "actually" know if a human could withstand a speed, such as light, even with a soft take off and landing? The atom slow down thing, that comes when you freeze them, right?

[D H]

Amazing.

I say:

Reality is one.

 

Or do you disagree even on this simple statement?

If by that simple statement you mean that there exists one unique reference against which all things can be judged, nope. Theory and observation say that this simple statement is simply wrong. There is no preferred reference frame.

[swansont]

Only trying to look at it conjecturally, but isn't atrophy our biggest problem with space flights at this time? And does anyone "actually" know if a human could withstand a speed, such as light, even with a soft take off and landing? The atom slow down thing, that comes when you freeze them, right?

 

Atrophy is because of weightlessness, not because of the speed.

 

The dilation effect you describe is backwards — cold means slow, and slow means smaller dilation effects. So what you describe is not what is happening.

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Consecutive posts merged

Yes, but in ten years at very close to C you could travel hundreds if not thousands of light years, to you the rest of the universe looks time dilated to them you do... which is real after you come back to you starting point? You have aged ten years they have aged thousands of years yet to you when you were traveling they looked as time dilated to you as you did to them but once the trip is over only your time dilation is real.

 

Yes. But rigney was implying that the humans and the spacecraft would somehow not feel the same dilation effects, and that's not the case.

[michel123456]

If by that simple statement you mean that there exists one unique reference against which all things can be judged, nope. Theory and observation say that this simple statement is simply wrong. There is no preferred reference frame.

 

We touched the cornerstone of our disagreement.

 

An astronomer somewhever on another planet observes you flat as a pancake and having a mass of billions tons.

You say that both reality of this astronomer and your reality are correct. In some sense, you say that reality is dependent of the observer, that reality is frame dependent, that physical reality is multiple.

 

I say it is utter nonsense.

 

I say reality is unique, that reality is correct where the observator is in the same FOR of the observed object.

 

In other words, that you are not flat as a pancake and that your mass is not increasing, that all those effects are only a question of appearence & measurement.

[Sisyphus]

And what is your basis for saying those things?

[swansont]

Restricting observation to objects at rest one's own frame of reference is very limiting.