What Happens in a Relativistic Particle Collision?

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Discussion Overview

The discussion revolves around the relativistic effects observed during particle collisions, particularly when two particles approach each other at speeds close to the speed of light. Participants explore the implications of different reference frames on the perceived location and timing of the collision.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions how the collision point appears to differ depending on the reference frame, suggesting that the collision would happen at different locations for the particles compared to a stationary observer.
  • Another participant argues that if the stationary observer sees both particles at equal distances, they would collide at the same point as perceived by the observer, implying agreement on the collision point across frames.
  • A participant notes that from Particle A's perspective, both the observer and Particle B would seem to approach at speeds close to light, raising questions about the perception of speed and collision timing.
  • Another participant introduces the velocity addition formula to explain how the speeds of the observer and Particle B would be perceived in Particle A's frame, suggesting that all parties would meet at the same location regardless of the frame chosen.

Areas of Agreement / Disagreement

The discussion features competing views on how the collision point is perceived in different reference frames, with no clear consensus reached among participants.

Contextual Notes

Participants express varying assumptions about the nature of relativistic speeds and the implications for collision timing and location, which remain unresolved.

itsjustme
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Suppose 2 particles are heading towards each other at a speed very close to the speed of light (relative to a stationary observer). Relative to the observer they would collide at a given point. But if you look at it relative to one or the other particle, the collission would happen elsewhere. What exactly happens?
 
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itsjustme said:
Suppose 2 particles are heading towards each other at a speed very close to the speed of light (relative to a stationary observer). Relative to the observer they would collide at a given point. But if you look at it relative to one or the other particle, the collission would happen elsewhere. What exactly happens?
Why do you think the collision would happen elsewhere? Suppose in the stationary observer's frame the two particles are at equal distances from the observer, so they both collide at the same position the observer is standing. Either particle sees the stationary observer coming toward it at close to the speed of light in its own frame, and the other particle coming toward it in back of the stationary observer at even closer to the speed of light, with both the stationary observer and the other particle reaching the first particle's position at the same moment, so they also agree that all three come together at the same point in space and time.
 
Well i was thinking that seeing as Particle A is moving at a speed close to that of light, relative to Particle A, both the observer and Particle B would appear to be going at that speed seiing as it is impossible to go faster than the speed of light.
 
itsjustme said:
Well i was thinking that seeing as Particle A is moving at a speed close to that of light, relative to Particle A, both the observer and Particle B would appear to be going at that speed seiing as it is impossible to go faster than the speed of light.
You can use the velocity addition formula...if both particles are moving at speed v relative to the middle observer, then in the particle's own frame the observer will be coming towards it at v while the second particle will come towards it a bit faster, at (v + v)/(1 + v*v/c^2). No matter what frame you choose the timing will work out so they all meet at the same spot though.
 
ok, thanks
 

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