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Saxby
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If i was standing on the Earth at rest and a spaceship traveling at 0.99c passed by and flashed a light for a very small amount of time would this time appear longer for me or the pilot of the spaceship?
It depends on when exactly the flash occurs.Saxby said:If i was standing on the Earth at rest and a spaceship traveling at 0.99c passed by and flashed a light for a very small amount of time would this time appear longer for me or the pilot of the spaceship?
ghwellsjr said:It depends on when exactly the flash occurs.
If a flash occurs as the spaceship is approaching the earth, the light will be blue shifted to a frequency that is about 14 times what it was sent at and would last for 1/14th of the time.
We'll assume you have special goggles or equipment to detect it.
If a flash occurs as the spaceship is departing away from the earth, the light will be red shifted to a frequency that is about 1/14th of what it was sent at and would last for 14 times longer.
Clearly, there is a point at which the flash could occur where it would last just as long for you as for the pilot, somewhere just overhead. But even then, the first part of it will be blue shifted and the latter part of it will be red shifted.
By the way, the previous answers are talking about time dilation which is not something that can be seen, only calculated, depending on the arbitrary frame of reference that you select.
Jeronimus said:Once again you confuse what people see with what is actually the case physically.
According to you, if an observer on Earth has his friend 1km away also at rest on earth, and the rocket was just between them when the flash happens, one of them would measure a higher time-interval while the other would measure a shorter time interval.
This confusion occurs because of the difference between SEEING something because of the way photons travel towards us at a limited speed and CONCLUDING when and where something happened (x/t) because you know physics.Let's say E1(x1/t1) / E2(x2/t2) start/end of flash. The flash lasted Δt = t2-t1 in the rocket frame.
In the frame the observer on Earth is at rest, those events will happen at
E1'(x1'/t1') E2(x2'/t2'). Δt' = t2' - t1' = Δt * γ
the well known formula, see here http://en.wikipedia.org/wiki/Time_dilation
Both observers on Earth will CONCLUDE, which is not the same as SEE, that the time interval between those two events is LONGER on Earth by the SAME amount, no matter if they stand in front, behind or right at where the rocket passes.
Jeronimus said:Indeed, if the two observers did not know much about photons and were only to rely on their local observation without knowing physics, they would SEE different time intervals for the flashes, depending on if they stand in front or behind, just like you hear a different sound of a racing car incoming vs moving away. Did the motor start making different sounds all of the sudden?
PAllen said:If I asked you 'what would you hear?', what would you say?
The OP used the word appear.
Jeronimus said:I assumed that when OP asked that question, he wanted to know something about relativity, this being the section of the forums, not about Doppler effects which would occur even if space was absolute.
So how would someone ignorant to SR possibly learn anything more than about doppler effects which happen in absolute space just as well, by reading ghwellsjr post?
Or are we to take questions asked by people trying to learn relativity just as an opportunity to stimulate our own ego by delivering the "right" answer?
I also assumed that the OP's question was about relativity and my specific answer would have been wrong "if space was absolute", as you put it.Jeronimus said:I assumed that when OP asked that question, he wanted to know something about relativity, this being the section of the forums, not about Doppler effects which would occur even if space was absolute.
So how would someone ignorant to SR possibly learn anything more than about doppler effects which happen in absolute space just as well, by reading ghwellsjr post?
Or are we to take questions asked by people trying to learn relativity just as an opportunity to stimulate our own ego by delivering the "right" answer?
The light flash from a spaceship is caused by the ignition of the rocket engines. When the engines are ignited, a large amount of fuel is burned, creating a bright burst of light.
The light flash is often seen during a spaceship launch because the rocket engines are ignited at this time. As the spaceship ascends into the atmosphere, the light flash becomes more visible as it reflects off the surrounding air and clouds.
The light flash from a spaceship is not harmful to humans. It is a natural byproduct of the rocket engines and does not emit any harmful radiation or particles.
The intensity of the light flash can vary during a spaceship launch due to factors such as the amount of fuel being burned, the angle of the sunlight, and the atmospheric conditions. It can also appear brighter or dimmer depending on the viewer's perspective.
The light flash from a spaceship does have scientific significance as it can provide valuable information about the rocket engines and their performance during the launch. Scientists can also use the data from the light flash to analyze and improve future spacecraft designs.