Intergalactic Travel || What is this?||Possible ways?! || All about Intergalactic travel ||¦¦

Intergalactic travel is the term used for hypothetical manned or unmanned travel between galaxies. Due to the enormous distances between our own galaxy the Milky Way and even its closest neighbors—hundreds of thousands to millions of light-years—any such venture would be far more technologically demanding than even interstellar travel. Intergalactic distances are roughly a hundred-thousandfold (five orders of magnitude) greater than their interstellar counterparts.

Stars in the Large Magellanic Cloud, a dwarf galaxy. At a distance of 163,000 light-years, the LMC is the third closest galaxy to the Milky Way.

The technology required to travel between galaxies is far beyond humanity's present capabilities, and currently only the subject of speculation, hypothesis, and science fiction.

However, theoretically speaking, there is nothing to conclusively indicate that intergalactic travel is impossible. There are several hypothesized methods of carrying out such a journey, and to date several academics have studied intergalactic travel in a serious manner.

The difficulties of intergalactic travel

Due to the size of the distances involved any serious attempt to travel between galaxies would require methods of propulsion far beyond what is currently thought possible in order to bring a large craft close to the speed of light.

According to the current understanding of physics, an object within space-time cannot exceed the speed of light, which means an attempt to travel to any other galaxy would be a journey of millions of earth years via conventional flight.

Manned travel at a speed not close to the speed of light, would require either that we overcome our own mortality with technologies like radical life extension or traveling with a generation ship. If traveling at a speed closer to the speed of light, time dilation would allow intergalactic travel in a timespan of decades of on-ship time.

Additional constraints include the variety of unknowns regarding the durability of a spaceship for such complex travel. Fluctuating temperatures as in the warm-hot intergalactic medium could potentially disintegrate future spacecraft if not properly shielded.

These challenges also mean a return trip would be very difficult. Therefore, all future studies on the risks and feasibility of intergalactic travel would have to include a wide range of simulations to increase chances of a successful payload.

Possible methods

Extreme long-duration voyages

Voyages to other galaxies at sub-light speeds would require voyage times anywhere from hundreds of thousands to many millions of years. To date only one design such as this has ever been made.

Hypervelocity stars

Theorized in 1988, and observed in 2005,there are stars moving faster than the escape velocity of the Milky Way, and are traveling out into intergalactic space. There are several theories for their existence. One of the mechanisms would be that the supermassive black hole at the center of the Milky Wayejects stars from the galaxy at a rate of about one every hundred thousand years. Another theorized mechanism might be a supernova explosion in a binary system.

These stars travel at speeds up to about 3,000 km/second. However, recently (November 2014) stars going up to a significant fraction of the speed of light have been postulated, based on numerical methods. Called Semi-Relativistic Hypervelocity Stars by the authors, these would be ejected by mergers of supermassive black holes in colliding galaxies. And, the authors think, will be detectable by forthcoming telescopes.

These could be used by entering into an orbit around them and waiting.

Stellar engines

Another proposal is to artificially propel a starin the direction of another galaxy.

Time dilation

While it takes light approximately 2.54 million years to traverse the gulf of space between Earth and, for instance, the Andromeda Galaxy, it would take a much shorter amount of time from the point of view of a traveler at close to the speed of light due to the effects of time dilation; the time experienced by the traveler depending both on velocity (anything less than the speed of light) and distance traveled (length contraction). Intergalactic travel for humans is therefore possible, in theory, from the point of view of the traveller.

Accelerating to speeds closer to the speed of light with a relativistic rocket would allow the on-ship travel time to be drastically lower, but would require very large amounts of energy. A way to do this is space travel using constant acceleration. Traveling to the Andromeda Galaxy, 2 million light years away, would take 28 years on-ship time with a constant acceleration of 1g and a deceleration of 1g after reaching half way, to be able to stop.

Going to the Andromeda Galaxy at this acceleration would require 4 100 000 kg fuel per kg payload using the unrealistic assumption of a 100% efficient engine that converts matter to energy. Decelerating at the halfway point in order to stop dramatically increases the fuel requirements to 42 trillion kg fuel per kg payload. This is ten times the mass of Mt Everest required in fuel for each kg of payload. As the fuel contributes to the total mass of the ship, carrying more fuel also increases the energy required to travel at a certain acceleration and extra fuel added to make up for the increased mass would further contribute to the problem.

The fuel requirements of going to the Andromeda Galaxy with constant acceleration means that either the payload has to be very small, the spaceship has to be very large or it has to collect fuel or receive energy on the way through other means.

Possible faster-than-light methods

The Alcubierre drive is a highly hypothetical concept that is able to impulse a spacecraft to speeds faster than light (the spaceship itself would not move faster than light, but the space around it would). This could in theory allow practical intergalactic travel. There is no known way to create the space-distorting wave this concept needs to work, but the metrics of the equations comply with relativity and the limit of light speed.

"Earth 🌍 like" Exoplanet is Discovered In The Nearest Star-System To Our Own

In the search for exoplanets, among all the “Hot Jupiters” and two-faced hellish domains, scientists hope more than anything to find Earth-like worlds, ones that may hold life. A truly breathtaking new Nature study has dramatically revealed that a second home may exist just over 4 light-years away, in the Alpha Centauri triple star system.

This new world dances around the red dwarf star Proxima Centauri, which is the closest star to our own Sun. Dubbed “Proxima b”, this exoplanet was discovered after painstaking years of analysis of the tiny movements of its host star in response to the gravitational pull of the planet itself. By picking apart these stellar wobbles, estimates of the planet’s mass and physical parameters could be made.

It orbits the star every 11.2 days at an incredibly short distance of 7.5 million kilometers (4.7 million miles). It’s tidally locked, which means that one side of the planet always faces the star, and the other remains in perpetual darkness. 

The planet, which is equivalent to 1.3 Earth-masses, is likely to be around 5 billion years old, based on the age of the star system it's residing in.

It’s possibly terrestrial, meaning that it has a rocky surface, and based on its temperature, it is possible for liquid water to exist at the surface. As we know from our own pale blue dot, where there is water, there is life. This means that Proxima b is likely to be the nearest possible home to life outside our own Solar System.

After all this time looking into the far reaches of space, we may have a second Earth sitting right next door in our own cosmic backyard. Although it’s too early to definitively state that this world is “Earth-like”, as the presence of an atmosphere and water have yet to be shown, chances aren’t unreasonable for both being present.

Many exoplanets have been found and many more will be found, but searching for the closest potential Earth-analogue and succeeding has been the experience of a lifetime for all of us,” lead author Dr Guillem Anglada-Escudé, a senior researcher at Queen Mary University London, said in a statement.

“Many people’s stories and efforts have converged on this discovery. The result is also a tribute to all of them.”

Proxima Centauri is a small red dwarf that is 88 percent less massive than our Sun, and 99.85 percent less luminous (true brightness). If Proxima b was at an Earth-Sun like distance from this red dwarf, it would be a cold, dead world – but the two are actually as close as 5 percent of the Earth-Sun distance.

This means that it’s relatively warm, and the team has calculated that its equilibrium temperature – its surface temperature without any atmospheric greenhouse effect being taken into account – is -40°C (-40°F). Although this is easily below the freezing point for water, the team notes that Earth’s equilibrium temperature is somewhat similar, at about -20°C (-4°F).

Importantly, Earth has an atmosphere, so the average global temperature is far above this, and liquid water exists on our planet’s surface. Does the same apply to Proxima b? Additional modeling shows that temperatures on Proxima b could be as high as 30°C (86°F) on its day-side and -30°C (-22°F) on its night-side if it does.

The terrestrial world, however, also receives 100 times more high-energy radiation than Earth does today, particularly in the form of X-rays. This could perhaps blow away a thin atmosphere or prevent life at the surface from evolving. Although this has long been thought by many to be a restriction for life on planets orbiting red dwarfs, this may not necessarily be the case here.

“What’s more interesting is the history of the planet,” co-author Ansgar Reiners, a professor of astrophysics at the Gottingen Institute for Astrophysics, told a press conference.

If the planet was always this close to the star, and the star had an early violent stage wherein it fired out vast amounts of high-energy radiation, then perhaps an atmosphere would never have been able to form. Alternatively, if the planet was far away at this point, or if the star never had such an energetic past, then an atmosphere could certainly have formed – one that, despite the high-energy radiation, may still exist today.

As for the possibility of liquid water, that is once again down to Proxima b’s mysterious past.

“It depends on the initial conditions. Either this planet formed dry, or it formed far away and brought a lot of water with it from beyond the ice line,” Anglada-Escudé added. “Perhaps it started dry and comets rained every once in a while down on it and brought more water with it. 

 There are viable models that lead to an Earth-like planet today.”

Just recently, a project designed to send an interstellar spacecraft to the Alpha Centauri system was announced. Backed by Stephen Hawking, the initiative, named Breakthrough Starshot, will surely get a huge boost from the news that a strong contender for a second Earth is hiding away in that very same star system..

This new world dances around the red dwarf star Proxima Centauri, which is the closest star to our own Sun. Dubbed “Proxima b”, this exoplanet was discovered after painstaking years of analysis of the tiny movements of its host star in response to the gravitational pull of the planet itself. By picking apart these stellar wobbles, estimates of the planet’s mass and physical parameters could be made.

It orbits the star every 11.2 days at an incredibly short distance of 7.5 million kilometers (4.7 million miles). It’s tidally locked, which means that one side of the planet always faces the star, and the other remains in perpetual darkness. 

The planet, which is equivalent to 1.3 Earth-masses, is likely to be around 5 billion years old, based on the age of the star system it's residing in.

It’s possibly terrestrial, meaning that it has a rocky surface, and based on its temperature, it is possible for liquid water to exist at the surface. As we know from our own pale blue dot, where there is water, there is life. This means that Proxima b is likely to be the nearest possible home to life outside our own Solar System.

After all this time looking into the far reaches of space, we may have a second Earth sitting right next door in our own cosmic backyard. Although it’s too early to definitively state that this world is “Earth-like”, as the presence of an atmosphere and water have yet to be shown, chances aren’t unreasonable for both being present.

Many exoplanets have been found and many more will be found, but searching for the closest potential Earth-analogue and succeeding has been the experience of a lifetime for all of us,” lead author Dr Guillem Anglada-Escudé, a senior researcher at Queen Mary University London, said in a statement.

“Many people’s stories and efforts have converged on this discovery. The result is also a tribute to all of them.”

Proxima Centauri is a small red dwarf that is 88 percent less massive than our Sun, and 99.85 percent less luminous (true brightness). If Proxima b was at an Earth-Sun like distance from this red dwarf, it would be a cold, dead world – but the two are actually as close as 5 percent of the Earth-Sun distance.

This means that it’s relatively warm, and the team has calculated that its equilibrium temperature – its surface temperature without any atmospheric greenhouse effect being taken into account – is -40°C (-40°F). Although this is easily below the freezing point for water, the team notes that Earth’s equilibrium temperature is very somewhat similar, at about -20°C (-4°F).

Importantly, Earth has an atmosphere, so the average global temperature is far above this, and liquid water exists on our planet’s surface. Does the same apply to Proxima b? Additional modeling shows that temperatures on Proxima b could be as high as 30°C (86°F) on its day-side and -30°C (-22°F) on its night-side if it does.

The terrestrial world, however, also receives 100 times more high-energy radiation than Earth does today, particularly in the form of X-rays. This could perhaps blow away a thin atmosphere or prevent life at the surface from evolving. Although this has long been thought by many to be a restriction for life on planets orbiting red dwarfs, this may not necessarily be the case here.

“What’s more interesting is the history of the planet,” co-author Ansgar Reiners, a professor of astrophysics at the Gottingen Institute for Astrophysics, told a press conference.

If the planet was always this close to the star, and the star had an early violent stage wherein it fired out vast amounts of high-energy radiation, then perhaps an atmosphere would never have been able to form. Alternatively, if the planet was far away at this point, or if the star never had such an energetic past, then an atmosphere could certainly have formed – one that, despite the high-energy radiation, may still exist today.

As for the possibility of liquid water, that is once again down to Proxima b’s mysterious past.

“It depends on the initial conditions. Either this planet formed dry, or it formed far away and brought a lot of water with it from beyond the ice line,” Anglada-Escudé added. “Perhaps it started dry and comets rained every once in a while down on it and brought more water with it. 

 There are viable models that lead to an Earth-like planet today.”

Just recently, a project designed to send an interstellar spacecraft to the Alpha Centauri system was announced. Backed by Stephen Hawking, the initiative, named Breakthrough Starshot, will surely get a huge boost from the news that a strong contender for a second Earth is hiding away in that very same star system.