Spaceship arriving at a planet

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Discussion Overview

The discussion revolves around the implications of Einstein's theory of relativity in the context of a hypothetical scenario involving a spaceship traveling at the speed of light towards a distant planet. Participants explore the behavior of light emitted from the spaceship's headlights and its interaction with the spaceship and the planet's surface.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions what observers on the planet would see when the spaceship's headlights are turned on while traveling at light speed.
  • Another participant asserts that light from the headlights will always arrive at the planet before the spaceship itself arrives, regardless of the spaceship's speed approaching light.
  • A subsequent post reiterates the claim that light will arrive before the spaceship, emphasizing that the spaceship can approach but never reach the speed of light.
  • Further speculation arises regarding a hypothetical spaceship made from massless material, suggesting that it could not slow down and would be perpetually traveling at light speed, although this material is acknowledged as non-existent.
  • Another participant points out that if the spaceship were massless, it would not have its own inertial rest frame, complicating the assertion that light from the headlights must travel at the speed of light in the ship's frame.

Areas of Agreement / Disagreement

Participants generally agree that light from the headlights will arrive before the spaceship, but there is disagreement regarding the implications of a massless spaceship and its effects on the behavior of light and reference frames.

Contextual Notes

The discussion includes assumptions about the nature of light and reference frames that may not be universally accepted. The hypothetical scenario of a massless spaceship introduces additional complexity that remains unresolved.

norvegicusbas
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Hello.
Me and a friend of mine were trying to get our heads around a few of the paradoxes that are found within Einstein's theory of relativity and he came up with something we could not work out ( though I am sure someone here will be able to :)

Imagine you were in a spaceship traveling at the speed of light towards a distant planet. This planet is very dark and the spaceship needs to put on its headlights to see exactly where this planet is. Soon as the headlights are switched on all those aboard the spaceship ( according to their reference frame ) see the light from the headlights shine off into the blackness of space at the speed of light and strike the planet. With the planet well lit from the spaceships headlights the ship continues to approach for an eventual landing. But what will the people on the planets surface see? Do they see the light from the headlights arriving at a point in time before the arrival of the spaceship?
 
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The light from the headlights of the spaceship will always arrive before the spaceship arrives. The spaceship can (at least hypothetically) approach the planet with a speed almost the speed of light but it can never reach the speed of light.
 
Passionflower said:
The light from the headlights of the spaceship will always arrive before the spaceship arrives. The spaceship can (at least hypothetically) approach the planet with a speed almost the speed of light but it can never reach the speed of light.

Thankyou Passionflower for your quick reply.
What would the outcome be though if the spaceship was made by some incredibly advanced alien race and could be constructed ( along with the passengers ) from a massless material?
 
norvegicusbas said:
Thankyou Passionflower for your quick reply.
What would the outcome be though if the spaceship was made by some incredibly advanced alien race and could be constructed ( along with the passengers ) from a massless material?
Well in that case it could never slow down and was doomed forever to travel at the speed of light. But clearly you must understand there is no such material.
 
norvegicusbas said:
Thankyou Passionflower for your quick reply.
What would the outcome be though if the spaceship was made by some incredibly advanced alien race and could be constructed ( along with the passengers ) from a massless material?
In that case the ship does not have its own inertial rest frame, so it is no longer true that the light from the headlights must move at c in the frame of the ship.
 

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