Speed and velocity have fascinated humankind for centuries. We are always trying to find ways to go faster, to break records, and push machines to their limits. But what actually is the fastest thing known in the universe? This article will examine some record-breaking speeds and discuss the theoretical and proven speed limits that govern our universe.
What does “fastest” mean?
When we talk about the “fastest” thing in existence, we need to precisely define what we mean by fast. Here are some key considerations:
- Velocity – The rate of change of position over time. For example, miles per hour or meters per second.
- Acceleration – The rate of change of velocity over time. How quickly can something increase its speed?
- Information Transfer – How rapidly can energy or information propagate from one point to another?
- Quantum Speeds – At the subatomic level, quantum particles can exhibit strange speeds and connections that defy classical physics.
So when we ask “what is the fastest?” the answer may depend on exactly what kind of speed we have in mind. In this article, we will focus primarily on velocity records and limits, but also touch on some other speed concepts.
Fastest Human-Made Objects
Humans have created some incredibly fast vehicles and machines. Here are some of the swiftest:
- Fastest plane – The NASA X-43A scramjet reached Mach 9.6 or nearly 7,000 mph in an experimental flight in 2004.
- Fastest manned plane – The North American X-15 rocket plane achieved Mach 6.7 or 4,500 mph in 1967 with pilot William J. Knight.
- Fastest rocket – The New Horizons probe launched in 2006 achieved a velocity of 36,400 mph as it passed Jupiter on its way to Pluto.
- Fastest human-made object – Helios 2, an unmanned probe, achieved 156,000 mph on its closest pass by the sun in 1976.
Engineers keep finding ways to break speed records through new aerodynamic designs, ultra-efficient engines, and high thrust rockets. But even our fastest man-made objects still move at just a tiny fraction of the cosmic speed limit (the speed of light).
Land Speed Records
For vehicles traveling on land, the limits are much lower due to drag and friction forces. Let’s look at the progression of the absolute land speed record over the last century:
| Year | Record Holder | Top Speed (mph) |
|---|---|---|
| 1906 | Fred Marriott – Steam Turbine Car | 127 |
| 1927 | Henry Seagrave – Golden Arrow | 231 |
| 1938 | John Cobb – Railton Special | 350 |
| 1947 | John Cobb – Railton Mobil | 394 |
| 1964 | Art Arfons – Green Monster | 434 |
| 1965 | Craig Breedlove – Spirit of America | 600 |
| 1997 | Richard Noble – Thrust SSC | 763 |
The current record of 763 mph was achieved in 1997 by the jet-powered Thrust SSC vehicle driven by Andy Green. It remains extremely challenging to reach such enormous speeds on land due to the physical forces involved.
Fastest Production Cars
While specialty vehicles hold the absolute records, some mass-produced sports cars can still achieve very high speeds:
- Bugatti Veyron Super Sport – 268 mph top speed
- Hennessey Venom GT – 270 mph
- Koenigsegg Agera RS – 277 mph
- SSC Tuatara – 316 mph (unverified)
The Koenigsegg Agera RS currently holds the Guinness World Record for the fastest production car, with a verified two-way average speed of 277.9 mph achieved in 2017. The car used a 5.0 liter twin-turbo V8 engine generating 1,360 horsepower.
Fastest Birds
Birds achieve remarkable speeds in air using only the power of their wings. Here are some of the highest recorded bird speeds:
- Spine-tailed swift – 105 mph in level flight
- White-throated needletail – 105 mph
- Eurasian hobby – 100 mph in stoops
- Frigatebird – 95 mph in display dives
- Peregrine falcon – 242 mph in dives (highest confirmed)
The peregrine falcon can achieve over 200 mph when diving from great heights to strike prey. Using its streamlined shape, modified wings, and incredible maneuverability, it is considered the fastest bird – and possibly fastest animal – on Earth.
Fastest Fish
Fish designed for speed can propel themselves through water at remarkable velocities. Here are some of the swiftest swimmers:
- Sailfish – 68 mph top speed
- Swordfish – 60 mph cruising speed
- Bluefin tuna – 43 mph sustained burst speed
- Marlin – 50+ mph in short bursts
The sailfish appears capable of swimming up to 68 mph in short sprints, faster than any other fish. Its streamlined, compressed shape, tall dorsal fin, and efficient side-to-side movements allow it to slice through the water at incredible speeds.
Fastest Land Animals
On land, four-legged animals can achieve impressive running speeds when they need quick acceleration and evasion capabilities. Here are some of the speediest land creatures:
- Cheetah – 71 mph recorded speed
- Pronghorn antelope – 61 mph
- Wildebeest – 50 mph
- Lion – 50 mph
- Thomson’s gazelle – 50 mph
The cheetah is the undisputed land speed champion, capable of reaching 71 mph at full exertion, faster than any other land mammal. Its flexible spine, enlarged heart and lungs, and claw grip give it phenomenal acceleration and agility.
Fastest Humans
The world’s fastest human runners reach much lower speeds, but are still incredibly quick compared to average people. Some records include:
- Usain Bolt – 27.8 mph during 100m sprint
- Florence Griffith Joyner – 23 mph during 100m sprint
- Hicham El Guerrouj – 21.4 mph during 1500m sprint
Usain Bolt holds the records for the 100m and 200m sprints, reaching nearly 28 mph at his peak speed during the races. No other human has exceeded this on foot. Elite sprinters can maintain over 20 mph paces for short distances.
Natural Speed Limits
As objects travel through air, water or space, the medium itself presents challenges that increase with speed. At incredibly high velocities, new effects start to emerge:
- Drag – Air resistance scales with speed and causes overheating at mach speeds.
- Turbulence – Shockwaves that can damage aircraft at transonic and supersonic velocities.
- Cavitation – Bubble formation in water at high speeds that damages propellers.
- Relativistic Effects – Strange effects from Einstein’s relativity at an appreciable fraction of the speed of light.
These effects place practical limits on attainable speeds through different media, even with powerful propulsion systems. But what are the ultimate speed limits set by the laws of physics?
Cosmic Speed Limit – Speed of Light
According to Einstein’s theory of special relativity, the speed of light in a vacuum is the absolute maximum velocity in the universe. The speed of light (c) is an incredible 186,000 miles per second or 670 million mph. Some reasons this speed limit exists:
- Light moves at c in every reference frame. If you are moving at 99% the speed of light relative to an object, light still passes you at c.
- Massless particles (like photons) must always travel at c based on equations derived from special relativity.
- As an object’s speed nears c, its mass approaches infinity. Accelerating an object with mass to light speed would require infinite energy.
No material particles with mass can reach the speed of light, although some particles have no mass (like photons). Nevertheless, c is considered the ultimate speed limit for everything in the universe.
Can the Speed of Light Change?
Some theories propose that the speed of light may not always have been precisely c in the history of the universe. Models based on quantum gravity suggest it could vary over extremely long timescales. However, any deviations that occurred just after the Big Bang would be locked in as a fixed value throughout space. The speed of light is believed to be locally constant throughout our observable universe.
Expanding Space Can Exceed Light Speed
While nothing can move through space faster than light speed, the expansion of space itself can exceed this limit. Distant regions of universe are expanding away from each other at speeds greater than the speed of light:
- Space expanded faster than light during the cosmic inflation period after the Big Bang.
- Today, galaxies at the edge of the observable universe recede from us at up to 10 times the speed of light, as more space gets added between us.
This does not violate relativity since nothing is moving through space at these speeds – space itself is simply expanding. But it shows that the speed of light is not a limit on all kinds of motion.
Quantum Entanglement Appears Instantaneous
One of the strangest effects from quantum physics is entanglement, where the properties of particles can stay connected no matter the distance between them. Changing one particle’s state simultaneously changes the other’s. This appears to occur instantly, even over vast distances, seemingly faster than light could travel between them. However, there is no way to control this effect to transmit information. So causality is not violated. Some explanations for this “spooky action” include:
- The particles influence each other through higher dimensions of space we cannot perceive.
- No physical influence occurs between entangled particles – the correlations are set at the moment of entanglement.
- An underlying quantum field connects particles and coordinates their states.
While the mechanism behind quantum entanglement remains mysterious, it demonstrates that surprising connections can exist below the scale of space and time. Such quantum effects hint at physics beyond our conventional theories.
Phase Velocities Can Exceed c
Another quantum effect that seems to exceed light speed is quantum wave function phase velocity. When wave peaks travel, the point of peak phase can move from one location to another faster than light would take to cover the same distance. However, this does not allow transmitting information faster than light. Some key points:
- Only the peak phase location moves – overall wave disturbance propagates at the group velocity.
- Phase velocities apply to the quantum wave function, not actual material particles.
- Phase velocities can exceed c only in media like atomic materials, not free space.
While superluminal phase velocities appear possible, they do not violate the principles of relativity or allow faster-than-light communication. The speed of light remains the limit for transmitting information.
Gravitational Waves Propagate at Light Speed
When accelerating masses disturb the shape of spacetime, they create ripples known as gravitational waves. First directly detected in 2015, these waves provide a powerful new astronomical tool. Gravitational waves propagate at precisely the speed of light. This equality has been verified to within less than one part in 1015 (quadrillionths) by measurements of gravitational and electromagnetic signals from colliding neutron stars.
Faster-Than-Light Travel in General Relativity?
Einstein’s theory of general relativity describes how matter warps spacetime to produce the force of gravity. While it solidly preserves lightspeed as a limit locally, some solutions to its equations appear to allow faster-than-light travel, like wormholes. However, upon closer analysis, these often permit closed timelike loops, resulting in causality violations. As a result, many physicists believe unknown quantum effects likely preserve causality in any actual realization in nature, preventing their use for superluminal travel.
Concluding Thoughts
Nothing discovered so far in the laws of physics or in experimental results definitively contradicts Einstein’s theory that the speed of light is the ultimate speed limit in our universe. While subtleties in quantum mechanics and cosmology may allow puzzling phenomena like entanglement and cosmic inflation, these do not undermine the light speed limit when causality and locality are considered. As far as all current knowledge indicates, the speed of light remains the fastest possible travel speed, cementing its place as one of the fundamental constants that shapes our understanding of physics and our universe.