Room in Spaceship: Apparent Paradox?

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In summary, the conversation discusses a thought experiment involving a room in a spaceship with lasers, a light detector, and a switch. The light turns on when both lasers hit the detector at the same time, but from different reference frames, it may appear that the light turns on or off. However, the light will always turn on regardless of the observer's perspective, as physical experiments should give the same results in all frames.
  • #1
Superstring
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Imagine a room in a spaceship. At each end, a laser is set up that points toward the center. At the center of the room there is a double-sided light detector that is connected to a switch. When the switch is flipped, it completes a circuit which causes a light-bulb to turn on. If both laser beams hit the detector at the same time, the switch is flipped and the light turns on. If they hit at different times, the light remains off. The lasers are activated a remote control, also stationed at the center of the room.

From the reference frame of someone inside the ship, if they were to turn on the lasers then the beams would hit the detector at the same time and they would see the light turn on. However, if someone in a passing spaceship (passing in the same direction as the laser beams) were to watch this, they would see the beams hit the detector at different times and the light would not turn on.

So does the light turn on or not? Or both, somehow?
 
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  • #2
Superstring said:
From the reference frame of someone inside the ship, if they were to turn on the lasers at the same time then the beams would hit the detector at the same time and they would see the light turn on.

I added the phrase in bold to clarify what I take you to mean here. The clarification is crucial, because it resolves the apparent paradox, like so:

Superstring said:
However, if someone in a passing spaceship (passing in the same direction as the laser beams) were to watch this, they would see the beams [STRIKE]hit the detector[/STRIKE] being turned on at different times [STRIKE]and the light would not turn on[/STRIKE] but still reaching the detector at the same time and they would also see the light turn on.

Again, I've added the corrections in bold and crossed out the parts that were incorrect i your statement of how things would look from the spaceship. So the light turns on regardess of who is doing the observing (as it should--actual physical experiments have to give the same results in all frames).
 
  • #3
PeterDonis said:
I added the phrase in bold to clarify what I take you to mean here. The clarification is crucial, because it resolves the apparent paradox, like so:



Again, I've added the corrections in bold and crossed out the parts that were incorrect i your statement of how things would look from the spaceship. So the light turns on regardess of who is doing the observing (as it should--actual physical experiments have to give the same results in all frames).

Thank you. That cleared up my confusion.
 

1. What is the apparent paradox in "Room in Spaceship: Apparent Paradox?"

The apparent paradox in this scenario is that the room in the spaceship appears to be both larger and smaller than it actually is at the same time.

2. How is this paradox possible?

This paradox is possible due to the effects of time dilation and length contraction in special relativity. As the spaceship moves at high speeds, the perception of time and space changes, resulting in the room appearing to be both larger and smaller from different perspectives.

3. Is this paradox only applicable to spaceships?

No, this paradox is not limited to spaceships. It can also occur in any scenario where objects are moving at high speeds relative to each other, such as in particle accelerators or moving vehicles.

4. Can this paradox be observed in real life?

Yes, this paradox has been observed in real life through experiments such as the famous "twin paradox," where one twin stays on Earth while the other travels in a spaceship at near-light speeds. When the traveling twin returns, they would be younger than the twin who stayed on Earth due to time dilation.

5. How does this paradox impact our understanding of space and time?

This paradox challenges our traditional understanding of space and time as fixed and absolute. It highlights the fact that our perception of reality is relative and can be influenced by factors such as motion and gravity. It also supports the theory of special relativity, which has been confirmed through numerous experiments and observations.

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