Why Tapping With a Stick Won't Beat the Speed of Light

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Homework Help Overview

The discussion revolves around the concept of transmitting information using a long stick to tap Morse code, exploring the implications of such an attempt in relation to the speed of light. It also examines the nature of intervals between two events in spacetime, questioning their classification as time-like, space-like, or light-like.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the feasibility of sending messages faster than light through tapping and question the nature of the intervals between two events. Some express uncertainty about the underlying concepts, while others suggest that sound travels slower than light.

Discussion Status

The discussion is ongoing, with participants exploring various interpretations of the problem. Some guidance has been offered regarding the speed of sound compared to light, and the classification of the events as time-like has been suggested, though not all participants agree on the simultaneity of the events.

Contextual Notes

Participants express difficulty in grasping the concepts involved, indicating a need for clarification on the fundamental principles of spacetime and the speed of light. There is also a mention of the original poster's struggle with conceptual explanations despite handling numerical questions effectively.

forty
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(1) A very long stick is used in an attempt to send messages faster than the speed of light by tapping Morse code on a distant observers forehead. Why will this attempt fail to send messages faster than the speed of light?

(2) An observer is born (event1), sits in the same place for 100 years, then dies (event2). Determine the interval between events 1 and 2. Is this a time-like, space-like or light-like interval? Can the two events be seen to be simultaneous in a different reference frame? Explain.

As for (1) I know that it can't but for the exact reasoning I don't really have a clue besides that nothing can travel faster than the speed of light.

For (2) I have no Idea. (However I don't think they can be seen to occur simultaneously as they occur in the same position.)

I'm sorry for being so vague and unclear but I have read through multiple texts and just can't seem to grasp this. Numerical questions I can handle but explaining the concepts does my head in. So any help or explanations would be VERY much appreciated.
 
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1. lol is funny, i suggest that when the morse code is tapped, the sound is much much slower then light, so light would be faster, compared to the how fast you hear the tapping... I am not sure, just an idea.

2. the events are timelike, since they only depend on time, and i don't think they can be simultaneous
 
for (1) if the stick is infinitely dense shouldn't the tap at one end be transmitted instantaneously to the other?
 
forty said:
for (1) if the stick is infinitely dense shouldn't the tap at one end be transmitted instantaneously to the other?

No. A shock wave travels at less that the speed of light even if density (or "stiffness") approaches arbitrarily large values in the limit.
 

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