Would Headlights Work At Light Speed

Can a car run at the speed of light? If it does, would headlights work at light speed?

It is one of the most frequently asked physics questions. Even famous comedian Steven Wright reflected on this topic during his first HBO special. But the premise is impossible because nothing can travel at a light speed.

Traveling at the speed of light is contradictory to Einstein’s Special Theory of Relativity. No object with mass (a physical body that shows resistance to acceleration and gravitational attraction to other similar bodies) can travel at or above the speed of light (c). When an object draws near c, its acceleration resistance (mass) grows to the point that it cannot reach c without an infinite amount of force.

We can only reach a hypothetical conclusion to what would happen to the headlights if a car travels at the light speed.

Would Headlights Work At Light Speed?

Only mass-less particles can travel at a light speed in a vacuum so a car cannot do that. But, as it is a hypothetical question, let’s assume that the car has turned into something mass-less, like a car of light.

Would headlights work at light speed
Headlights will work at the speed of light. (Photo Source: besthdwallpaper)


Let’s discuss a couple of scenarios to see would headlights work at light speed or not.

1. You Cannot Turn The Lights On When The Car Runs At A Light Speed

Traveling at the light speed means that the time is frozen. When sitting inside the car, you cannot flick on the beams or even do anything else as the time stops entirely. On the contrary, the time of the universe will pass instantly.

But, the light could already be on before reaching the c, right? In that case, you will see the light but not in its usual color. The frequency of the light changes when the velocity increases. At 50% of the light speed, the reflection of the light you will get is the UV ray. At 99.99%, the reflected light won’t be visible to any human eye, but an X-ray detector. If the car speeds up to c with the headlights on, you will see the light but in a different color spectrum.

2. What Happens When You Drive Just Below The Light Speed?

When you are traveling at slightly less than the speed of slight, you can flick the headlight switch on. Will the headlights work at that speed? Yes, they will.

The light coming from the headlights will appear like moving away from you at a light speed—similar to what we experience when driving with the lights on in a normal condition. The speed of the light beam will be faster enough to race ahead of the vehicle. However, the distance will appear compressed in that high-speed condition.

Would headlights work at light speed
Light’s color spectrum will be different. (Photo Source: deviantart)

>> We have used Japanese cars for sale whose headlights work perfectly. Click here!!! <<

The Bottom Line

Would headlights work at light speed? Yes, they will under certain conditions. But the headlights won’t illuminate anything in front at that speed because the velocity of the vehicle, you (as the passenger), and the light is equal. If you are outside the car and facing the light while traveling at a light speed, you still won’t see the illumination because of the equal velocity.