What Near-Light-Speed Travel Would Feel Like
In an idealized light-speed spaceship, the trip could take almost no time for travelers because the distance ahead contracts, while Earth still sees motion at light speed.
Details
Special relativity produces a strange result when travel gets extremely close to the speed of light. An observer on Earth can measure a huge distance between two destinations, while a traveler moving at an enormous fraction of light speed measures that distance as shorter because of length contraction. The faster the ship moves, the stronger this effect becomes. Time dilation also means less time passes for the traveler than for people who remain on Earth. In the idealized limit of exactly light speed, the travel time from the travelers perspective is often described as zero, but there is an important physical catch: a spaceship with mass cannot actually reach the speed of light. Only massless particles can move at light speed, and they do not have a valid rest frame in which to experience the trip. So the original claim works best as a thought experiment about the limiting behavior of special relativity, not as a practical description of a possible spacecraft. For speeds extremely close to light speed, however, the effects are real and can make enormous journeys take much less proper time for the travelers than they do for people left behind.
More videos
- Why Snapping Your Fingers Makes Such a Sharp Sound
The sound of a finger snap comes mainly from your middle finger striking your palm, with the skin and air helping turn that motion into a sharp pop.
Tags: Physics
- Gravity Travels at the Speed of Light
Changes in gravity travel at the speed of light, and observations of a neutron star merger showed gravitational waves and light arriving together after 130 million years.
Tags: Physics
- The Ghost Particles Passing Through You Every Second
Trillions of neutrinos pass through your body every second, almost never interacting, while scientists build huge detectors to study these elusive particles.
Tags: Physics
- Phonons: The Quantum Particles of Vibrations in Matter
Phonons are quasiparticles that describe quantized vibrations in crystal lattices, and quantum sensors can measure how these vibrations lose coherence.
Tags: Physics
- Earth’s Core Is About 2.5 Years Younger Than Its Surface
Gravity makes time pass slightly slower deep inside Earth, leaving the core about 2.5 years younger than the surface after 4.5 billion years.
Tags: Physics
- Bananas Naturally Produce Tiny Amounts of Antimatter
Bananas contain trace potassium-40, whose rare radioactive decay produces a positron, an antimatter particle, about once every 75 minutes.
Tags: Physics
- Sonar Revealed a Phantom Seafloor Made of Migrating Fish
Early sonar operators found a false seafloor that moved with daylight and moonlight. It turned out to be a huge layer of lanternfish and other sea life.
Tags: Physics
- Why Ancient Roman Lead Is Valuable for Ultra-Sensitive Detectors
Ancient Roman lead from shipwrecks has extremely low radioactivity, making it valuable as shielding for highly sensitive scientific equipment.
Tags: Physics
- Why Apollo Astronauts Saw Flashes With Their Eyes Closed
During Apollo 11, an astronaut saw flashes with his eyes closed, and researchers linked the strange vision to high-energy particles passing through the eye.
Tags: Physics
