# Thought:

What could happen if a needle enters the Earth's atmosphere at the speed of light?

MY opinion = It would cut the earth the size of a needle and we wouldn't notice

MY opinion 2 = The world would disappear

Note by Ömer Ertürk
4 months, 1 week ago

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Because of special relativity, the needle can have an arbitrarily high amount of kinetic energy, depending on how close it is traveling to the speed of light. Assuming its speed is equal to the speed of light to within one part in $10^{10000}$, for example, I think it will probably obliterate the Earth.

- 4 months, 1 week ago

Sensible

- 4 months, 1 week ago

Scariest part, we won’t even see it coming

- 4 months, 1 week ago

@Steven Chase I want to know your opinion?

- 4 months, 1 week ago

Neutrinos can pass through thousands of kilometers of solid matter without interacting, but a metal object can't. The needle will rip apart violently and release a large fraction of its kinetic energy within the Earth. The same is true with bullets. If you fire a relatively low velocity bullet (ex: from a 9mm pistol) into a pool of water, the bullet remains intact and can travel a considerable distance through the water due to its relatively low speed. But if you fire a high-powered rifle into the water (with a much faster bullet), the bullet tears apart immediately upon entering the water, and releases all its kinetic energy in a big explosion. I saw that experiment performed on a show called MythBusters.

- 4 months, 1 week ago

Here is the clip

- 4 months, 1 week ago

@Steven Chase Amazing You are right.my imagination was wrong.
So instead of dropping nuclear bomb ,one should focus on how to throw a particle with a greater speed .
It will help in war ,

- 4 months, 1 week ago

Speaking of nuclear, why can’t the needle initiate a nuclear reaction, the kinetic energy is approaching ∞, so even a fraction of it can easily start nuclear reactions

- 4 months, 1 week ago

But if it obliterates the earth, these small nuclear reactions can be neglected

- 4 months, 1 week ago

there is a youtube video that explains what happens when a grain of sand with speed close to the speed of light hits the earth.
he assumes it will create a big crater, but the mass is still to low to create more damage.

- 4 months ago