# Special relativity and flash bulbs

• matness
In summary, the conversation discusses the concept of simultaneous flashing of bulbs fixed at all lattice points in an inertial frame. The question arises of what an observer at the origin would see when the bulbs all flash at once. It is clarified that the bulbs are flashing simultaneously according to their synchronized clocks, but the observer may not see them all flash at the same time due to the effects of light travel time. The concept of multiple inertial frames is discussed, with the understanding that each frame has an observer at every possible position.
matness

## Homework Statement

this is a problem from rindler

Suppose there are flush bulbs fixed at all lattice points of some inertial frame and suppose they all flash at once .what actually seen by an observer sitting at the origin?

## The Attempt at a Solution

i don' t understand the question itself ."they all flash at once": relative to whom

matness said:
"they all flash at once": relative to whom
Relative to the given inertial frame.

ok. But what changes then relative to the observer? The observer should see everything same. If it was so ,then i think rindler would not use this as a problem.there must be some poinnt that i missed

You are confusing (1) the bulbs flashing simultaneously, with (2) a person seeing (receiving the light from) the flashes simultaneously.

Example: You are at point x = 0. One bulb is at point x =0, another is at point x = 1 light year. If the two bulbs flash simultaneously (at the same time according to their synchronized clocks), when do you see the light from each bulb?

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So i have to think two inertial frames: one of observer's and the other one synchronized stars'. And therefore only the bulbs which are at the same distance to the observer will flash simultaneously.and the further ones will flash later
Is it correct?

It's not a matter of multiple inertial frames--there is only one frame in this problem. Instead it's a matter of realizing that in order to interpret raw observations, one must account for light travel time.

Generally, in relativity thought experiments, one imagines an inertial frame as having zillions of observers (each with his own synchronized clock) located at every possible position. Thus when the lights flash, there will be a co-located observer able to confirm that the lights all flashed at the same time. (The various observers just compare their clock readings later.) But if an observer sees some event happen that is remote from him, he must subtract the light travel time from the time when he saw the light to find the actual time (according to clocks in his frame) that the event happened.

Of course, observers in a different frame (moving with respect to the bulbs) will disagree that the bulbs flashed simultaneously.

## 1. What is special relativity?

Special relativity is a theory developed by Albert Einstein that explains the relationship between space and time, and how they are affected by the motion of an observer.

## 2. How does special relativity relate to flash bulbs?

Special relativity affects the perception of time and distance for objects moving at high speeds, such as flash bulbs. As an object moves closer to the speed of light, time slows down for the object and the distance it travels appears to shorten.

## 3. Can special relativity explain the behavior of flash bulbs?

Yes, special relativity can explain how the behavior of flash bulbs changes when they are moving at high speeds. The theory takes into account the time dilation and length contraction effects, which can impact the brightness and duration of the flash.

## 4. How does the speed of light play a role in special relativity and flash bulbs?

The speed of light is a fundamental constant in special relativity and plays a crucial role in the theory. It is the maximum speed at which any object can travel, and as an object approaches this speed, its perception of time and distance changes, affecting its behavior, including that of flash bulbs.

## 5. Is special relativity a proven theory?

Yes, special relativity has been extensively tested and has been proven to be an accurate description of the relationship between space and time. Its predictions have been confirmed through experiments and observations, making it one of the most well-established theories in modern physics.

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