Nothing can travel faster than 300,000 kilometers per second (186, 000 miles per second). Only massless particles, including photons, that make up light, can reach this speed. It is impossible to accelerate a material object to the speed of light because it would take an infinite amount of energy to do so. The closest star to Earth is Proxima Centauri, located about 4.25 light-years away, or about 25 trillion miles (40 trillion km).
The fastest spacecraft in history, the Parker Solar Probe, now in space, will reach a maximum speed of 450,000 miles per hour. This means it would take just 20 seconds to get from Los Angeles to New York City at that speed. However, it would take about 6,633 years for the solar probe to reach the nearest neighboring solar system to Earth. In 1968, Freeman Dyson proposed an interstellar spacecraft that used nuclear pulse propulsion and fusion detonations of pure deuterium with a very high fraction of fuel consumption. This would allow a vehicle to move through space-time at a maximum speed of one meter per second and reach point B in about one second.
Knowledge of the properties of the interstellar gas and dust through which the vehicle must pass is essential for the design of any interstellar space mission. Interstellar travel is the hypothetical journey of a spacecraft from one star system, lone star, or planetary system to another. It is expected to be much more difficult than interplanetary space flights due to the large difference in the scale of the distances involved. The crew of an interstellar ship would face several major dangers, including the psychological effects of prolonged isolation, the physiological effects of extreme acceleration (if it exceeded the acceleration of 1 g), the effects of exposure to ionizing radiation from space and possibly from the ship's engines, and the physiological effects of weightlessness on muscles, joints, bones, the immune system and eyes. A radio frequency (RF) resonant cavity thruster is a device that is claimed to be a spacecraft thruster. At that rate, it will be nearly three times faster than previous record holders, a pair of spaceships called Helios probes that studied the Sun in the 1970s.
In this scheme, a 30-kilometer secondary sail is deployed at the rear of the spacecraft, while the large main sail is separated from the ship to continue moving forward on its own. Based on work carried out between the late 1950s and early 1960s, it has been technically possible to build spaceships with nuclear impulse engines. However, they won't approach another star for hundreds of thousands of years, long after they've stopped operating (although, in theory, the Voyager Gold Disk could be reproduced in the unlikely event that an alien civilization recovers the spacecraft). Interstellar space is not completely empty; it contains trillions of icy bodies ranging from small asteroids (Oort cloud) to possible rogue planets. General relativity states that space and time are merged and that nothing can travel faster than the speed of light. Several strategies have been proposed to address these problems associated with interstellar travel, ranging from giant arks that would transport entire societies and ecosystems to microscopic space probes.
A wormhole is a conjectural distortion in space-time that could connect two arbitrary points in the universe through an Einstein-Rosen bridge.
