Try this--I think that it is attributable to Einstein.

Imagine a very very long electric fence with a cow touching it every 100,000 miles or so

If the fence was that long the cow could touch it and would not feel a thing .

The wire would have to be so thick it could not be made .

Electicity does not travel though wire well.

:))

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Glenn ,my son,--old cow

If the fence was that long the cow could touch it and would not feel a thing .

The wire would have to be so thick it could not be made .

Electicity does not travel though wire well.

Wrong on all counts. Is this getting to be a habit for you? It is of course a thought experiment that sheds light (Pun intended) on the question at hand. It speaks to the question of simultaneity of events and it depends on where the observer is placed in the inertial reference frame. The question of what is actually happening and what appears to be happening is at the heart of this overall question. i.e. does length actually contract or does it just appear to contract--very subtle questions that are not well dealt with by most physics texts and professors.

Thought experiments gives me headache:)
Especially this one.
The observer and the observed has different timeframes...
Actually all objects in the universe has different timeframes.
Some even say that the history still exists and the future is already there.
It depends if you travel or not.

None of us are likely to know the answer in our lifetimes, so why all this wringing of hands?

We have inquisitive minds because of our intelligence, hence not knowing the truth is rather frustrating.

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rOZZ
Music
Pictures

Well here's a thought that may clarify or muddy up the question. If an object (say a tennis ball) were travelling very near the speed of light relative to an observer on Earth we say that it would take an infinite (or extremely large) amount of energy to accelerate it much further. However, a person traveling along with that object would be able to accelerate it quite easily with a little push.

How do you reconcile theory, observation and reality ??

How do you reconcile theory, observation and reality ??

An individual can only do that in his or her own mind I think.

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rOZZ
Music
Pictures

Well here's a thought that may clarify or muddy up the question. If an object (say a tennis ball) were travelling very near the speed of light relative to an observer on Earth we say that it would take an infinite (or extremely large) amount of energy to accelerate it much further. However, a person traveling along with that object would be able to accelerate it quite easily with a little push.

How do you reconcile theory, observation and reality ??

The person traveling along with the tennis ball is already at the same energy level. A push would be the current energy of motion plus what was extended, meaning you wouldn't have to start from zero.

Steve

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Warning, addicted to SETI crunching!
Crunching as a member of GPU Users Group.
GPUUG Website

Yes, but at close to light speed, the increase is limited to light speed minus your current speed.

Steve

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Warning, addicted to SETI crunching!
Crunching as a member of GPU Users Group.
GPUUG Website

Well here's a thought that may clarify or muddy up the question. If an object (say a tennis ball) were travelling very near the speed of light relative to an observer on Earth we say that it would take an infinite (or extremely large) amount of energy to accelerate it much further. However, a person traveling along with that object would be able to accelerate it quite easily with a little push.

How do you reconcile theory, observation and reality ??

No, that is wrong!

2 travel faster, u've 2 put so much more energy in2 d sys...so a little push, just will not do it!
it's like driving a car...if u want 2 drive 100km/h s 30-40HP will do...if u wanna do a 200km/h a 100+HP will have to do it! 4 a 300km/h car s 400+HP is needed! 4 400km/h a 1000+HP...etc.
;)

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non-profit org. Play4Life in Zagreb, Croatia, EU

Well, my son.

The tennis ball and the person travelling near the speed of light will not know that they are moving that fast unless they can establish a reference point. If they were in a closed room with no view of the outside they would think that they are stationary--so will all the equations that govern motion for them. So you must ask: their speed is relative to what frame of reference ?? If we were blind or in a closed box for all we would know our galaxy itself might be moving close to the speed of light.

We here on Earth are spinning at hundreds of miles per hour. We are travelling around the sun at 66,000 miles per hour and we also travel around the galaxy at around 500,000 miles per hour. The galaxy itself moves toward other galaxies at about 750,000 miles per hour. Unless we could look out and establish a reference point we would think that we were stationary and therefore not moving at all. Careful measurements on the speed of light and the force required to accelerate an object would not reveal any of these motions from within our closed room.

Quod Erat Demonstratum

More to ponder.

Is an electron a black hole ? (check the Schwarzchild radius.)
Are we moving towards Andromeda or are they moving toward us ? If we are both moving then which is travelling faster--how can you tell.

How does a thermos know whether to keep a liquid hot or to keep it cold. (LOL)

Is an electron a black hole ? (check the Schwarzchild radius.)

How does a thermos know whether to keep a liquid hot or to keep it cold. (LOL)

The Schwarzschild radius of an electron is 1.35x10-57 meters.
That is 8.31x10-22 Planck lengths.
Nothing can be so incredible small.

According to the generalized uncertainty principle (a concept from speculative models of quantum gravity), the Planck length is, in principle, within a factor of 10, the shortest measurable length – and no theoretically known improvement in measurement instruments could change that.
In some forms of quantum gravity, the Planck length is the length scale at which the structure of spacetime becomes dominated by quantum effects, and it is impossible to determine the difference between two locations less than one Planck length apart. The precise effects of quantum gravity are unknown; it is often guessed that spacetime might have a discrete or foamy structure at a Planck length scale.

A thermos knows this:
Heat cannot spontaneously flow from a colder location to a hotter location.

A thermos knows this:
Heat cannot spontaneously flow from a colder location to a hotter location.

Oooh we have intelligent Thermos's. Got an Amazon link?

Thats the Second Law of Thermodynamics:)

Well, my son.

The tennis ball and the person travelling near the speed of light will not know that they are moving that fast unless they can establish a reference point. If they were in a closed room with no view of the outside they would think that they are stationary--so will all the equations that govern motion for them. So you must ask: their speed is relative to what frame of reference ?? If we were blind or in a closed box for all we would know our galaxy itself might be moving close to the speed of light.

We here on Earth are spinning at hundreds of miles per hour. We are travelling around the sun at 66,000 miles per hour and we also travel around the galaxy at around 500,000 miles per hour. The galaxy itself moves toward other galaxies at about 750,000 miles per hour. Unless we could look out and establish a reference point we would think that we were stationary and therefore not moving at all. Careful measurements on the speed of light and the force required to accelerate an object would not reveal any of these motions from within our closed room.

Quod Erat Demonstratum

that is d problem in ur thought!

why?
we do travel around a Sun @ tremendous speed - BUT we r protected by Sun winds & storms by Magnetic field of Earth & Atmosphere!
we do travel @ even more tremendous speed around our Galaxy - BUT we r protected by Magnetic field of Sun, proved by Voyager mission!

another proof:
calculate d FORCE needed by Voyager mission 2 get out of Solar sys...it's not small @ all!
;)

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non-profit org. Play4Life in Zagreb, Croatia, EU

The second law of thermodynamics states that every natural thermodynamic process proceeds in the sense in which the sum of the entropies of all bodies taking part in the process is increased. In the limiting case, for reversible processes this sum remains unchanged.

For the layman - courtesy of Janne - that all means that Thermos's are clever!

All atoms follow universal laws of physics.
We humans are made of atoms.
Does that mean that atoms are clever?

Actually some atoms are rogues because the universe is not perfect.
We wouldn't exist in a perfect universe.

Heat cannot spontaneously flow from a colder location to a hotter location

How do it know ? (LOL)

It's very hard to visualize and to understand travelling in space at high speed.
Speed is as we all well know relative.

It's my belief that every object in our spacetime has the speed of light.
An observer with an different speed compared to the observed however sees it differently.
That's because time changes between the observer and the observed.
However the observer and the observed doesn't notice any difference in their own spacetime frames.

"The world is full of obvious things which nobody by any chance ever observes."

Heat cannot spontaneously flow from a colder location to a hotter location

How do it know ? (LOL)

Well. Try swimming near a waterfall:)
We know that we shouldn't but sometimes it happens.

Lets say that hypothetically we develope space vehicles that can accelerate to 75% of the speed of light. Two are built and are launched in opposite directions and after achieving their top speed will the crews be able to see each other? Does their apparent speed relative to each other exceed the speed of light?

Just remembered that similar explanation 2 what we're saying is a Picard maneuver, here:
http://en.memory-alpha.wikia.com/wiki/Picard_Maneuver
;)

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non-profit org. Play4Life in Zagreb, Croatia, EU