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Light travels at 299,792,458 meters per second in vacuum — the universal speed limit. Nothing with mass can reach this speed. Light simultaneously behaves as a wave (producing interference and diffraction) and as particles (photons — demonstrated by the photoelectric effect). This wave-particle duality is one of quantum mechanics' most mind-bending features.
Light from the Sun takes 8 minutes to reach Earth; from the nearest star, 4.2 years; from the Andromeda Galaxy, 2.5 million years. When we look at distant galaxies, we see them as they were in the past — the universe is a time machine. Visible light is a tiny slice of the electromagnetic spectrum, between infrared and ultraviolet. Different frequencies produce different colors; wavelengths range from 380nm (violet) to 700nm (red).
# Top 10 Light Physics facts
- 1Light from the Sun is 8 minutes old when it reaches us — when you look at the Sun, you see its past
- 2The fastest human-made object (Parker Solar Probe) travels at 690,000 km/h — still only 0.064% of light speed
- 3Photons have no mass and experience no time — from a photon's perspective, it travels no distance and takes no time
Fascinating Facts
- ◆Light from the Sun is 8 minutes old when it reaches us — when you look at the Sun, you see its past
- ◆The fastest human-made object (Parker Solar Probe) travels at 690,000 km/h — still only 0.064% of light speed
- ◆Photons have no mass and experience no time — from a photon's perspective, it travels no distance and takes no time
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