My Morse Code FTL Scissors Challenge

[AV1611VET]

I have a pair of scissors that stretches from Earth to Alpha Centauri.

By opening and closing them, I communicate to someone there via morse code.

Is this an example of faster-than-light communications?

 

[Yttrium]

Keep in mind that the motion has to be transmitted down the atoms of the scissors, so no, the end would open years afterwards.

But then again, the scissors would break from the stress, or the gravitational pull from the scissors would wreck the solar systems.

 

[Colo Millz]

Unfortunately rigid bodies don't exist in relativity.

Fun thought though.

 

[AV1611VET]

Keep in mind that the motion has to be transmitted down the atoms of the scissors, so no, the end would open years afterwards.

Interesting -- thanks for the info.

Could we assume zero Shannon entropy?

 

[AV1611VET]

Unfortunately rigid bodies don't exist in relativity.

Fun thought though.

Thanks.

 

[Yttrium]

Interesting -- thanks for the info.

Could we assume zero Shannon entropy?

That would result in no transmission of information...

 

[AV1611VET]

That would result in no transmission of information...

I thought you said the "end would open years later"?

 

[Tuur]

I have a pair of scissors that stretches from Earth to Alpha Centauri.

By opening and closing them, I communicate to someone there via morse code.

Is this an example of faster-than-light communications?

Um...This dates back to at least the waning days of Science Digest and probably before. Given that Archimedes supposedly said that give him a long enough lever and a place to set the fulcrum and he could move the world, scissors longer than 4 light years isn't a hypothetical deal breaker. If you could somehow open and close the scissors so that the blades move at light speed, the point of intersection still only arrives at the end when the tips of the scissors do. But since they are moving no faster than the speed of light, the point of intersection doesn't get there before the tips meet.

 

[essentialsaltes]

If you had a powerful laser pointer and shone it on the face of the moon and wiggle it back and forth, the spot can move faster than light.

But then the transdimensional cats attack it.

 

[DialecticSkeptic]

Keep in mind that the motion has to be transmitted down the atoms of the scissors, so no, the end would open years afterwards.

Move the scissor handles apart here (somehow) and the tips would finally part some 218,000 years later.

But forget Alpha Centauri. It is hard enough to grasp that a pair of scissors just 12 kilometers long would not respond instantly. Picture scissor blades that are 12 inches wide and one inch thick. Using ChatGPT to crunch the numbers, and modeled as a Euler–Bernoulli beam (because it approximates flexural waves), the tips of the scissors 12 km away wouldn't begin to part until roughly three minutes after I moved the handles at my end! That is crazy to think about.

Three minutes!

ChatGPT also tells me the mass of the scissors would be well over a million tons, taking roughly 100 Falcon Heavy rockets on each blade handle to move them apart—if they were in space (zero gravity).

 

[AV1611VET]

Using ChatGPT to crunch the numbers, and modeled as a Euler–Bernoulli beam (because it approximates flexural waves), the tips of the scissors 12 km away wouldn't begin to part until roughly three minutes after I moved the handles at my end!

I find that hard to believe.