Chapter 1: The Concept of a Long Lever

A thought-provoking question recently crossed my path: Is it possible to send information quicker than light by manipulating an extraordinarily long lever? Imagine constructing a lever that extends one light year in length. If we were to act on one end, wouldn’t the other end respond instantaneously? For instance, if we oscillate the lever using Morse code, could the information travel faster than light?

As established in physics, the speed of light is the ultimate limit for any object that has mass. Consequently, it follows that information cannot be conveyed at a speed surpassing that of light.

Source: sciencelet.com

At first glance, the premise seems reasonable. So, what is the flaw in this reasoning? Recall from middle school physics that the motion of the second arm of the lever occurs simultaneously with that of the first. This is a fundamental misunderstanding by the questioner—they assume that both arms of the lever move at the same instant.

Interestingly, why was a light year chosen as the length? If movements were genuinely simultaneous and information could be transmitted instantly, the distance wouldn’t matter—whether it’s 1 meter or a light year, instant transmission is still faster than light.

The reality is that applying force to one side of the lever creates longitudinal mechanical waves that travel through the lever. The speed of these waves is determined by the material's density and elasticity, and is equivalent to the speed of sound within that substance. This speed is inevitably lower than that of light, which means that the motion of the second arm will always lag behind, determined by the distance of the lever divided by the speed of these waves.

In practice, if you select the appropriate material, this phenomenon can be readily observed. For example, when manipulating a yoyo, as shown in the video, it's evident that the second end doesn't begin to move until the oscillation reaches it.

Read also: Why is the speed of light exactly 300,000 km/s?

Thus, despite the allure of using a lengthy lever for instantaneous information transmission, it remains unattainable. A disappointing reality, indeed.

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Chapter 2: Examining the Possibility of Faster-than-Light Transmission

The first video titled "I Think Faster Than Light Travel is Possible. Here's Why." delves into the arguments surrounding faster-than-light travel and the scientific theories that support or challenge this idea.

The second video, "Faster Than The Speed Of Light!...Or Not?" critically analyzes claims of superluminal speeds and presents evidence regarding the limitations imposed by the laws of physics.