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

AI Thread Summary
Tapping Morse code on a distant observer's forehead with a long stick cannot transmit messages faster than the speed of light because sound waves travel slower than light. The attempt fails as even an infinitely dense stick cannot transmit a tap instantaneously; shock waves still propagate at sub-light speeds. The interval between an observer's birth and death is classified as time-like since it is determined solely by time, and these events cannot be simultaneous in any reference frame. The discussion emphasizes that while concepts can be complex, the fundamental principles of relativity and wave propagation remain clear. Understanding these concepts is essential for grasping the limitations imposed by the speed of light.
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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