Practically, we cannot even imagine thinking of the end of space. It is a void where the multiverses lie. Our universe alone is expanding in every direction and covering billions of kilometres within seconds. There is infinite space where such universes roam and there is actually no end.
Roughly 1 trillion years from now, the last star will be born. In about 100 trillion years, the last light will go out. The bad news is that the universe is going to die a slow, aching, miserable death. The good news is that we won't be around to see it.
If the universe is infinite in size, you don't really need to worry about this conundrum. The universe, being all there is, is infinitely big and has no edge, so there's no outside to even talk about.
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.
The trite answer is that both space and time were created at the big bang about 14 billion years ago, so there is nothing beyond the universe. However, much of the universe exists beyond the observable universe, which is maybe about 90 billion light years across.
We could think of the universe as a sphere expanding indefinitely and infinitely. Or it might curve and bend in ways that could make it a closed system (like a donut), where if you were to travel in a straight line for long enough, eventually you'd end up back where you started: space would be finite.
The expansion starts off fast, and there isn't enough matter and energy to overcome that initial expansion. The expansion rate drops but never reaches zero; the Universe expands forever and ends in a Big Freeze.
Firstly, it is a future collision with another galaxy, Andromeda. The galaxies will pass through each other, merge into one gigantic galaxy and all star clouds will flash into a star formation. But there are also some issues, for instance, hot large blue stars, a blasting gas, a quasar, radiation.
So, to leave our Galaxy, we would have to travel about 500 light-years vertically, or about 25,000 light-years away from the galactic centre. We'd need to go much further to escape the 'halo' of diffuse gas, old stars and globular clusters that surrounds the Milky Way's stellar disk.
Proxima Centauri is 4.2 light-years from Earth, a distance that would take about 6,300 years to travel using current technology.
We can't smell space directly, because our noses don't work in a vacuum. But astronauts aboard the ISS have reported that they notice a metallic aroma – like the smell of welding fumes – on the surface of their spacesuits once the airlock has re-pressurised.
By 1014 (100 trillion) years from now, star formation will end, leaving all stellar objects in the form of degenerate remnants. If protons do not decay, stellar-mass objects will disappear more slowly, making this era last longer.
As it stands, the multiverse exists outside our current scientific understanding of reality. Theoretical physics suggests a multiverse is a hypothetical grouping of multiple universes.
NASA's Nancy Grace Roman Space Telescope, which will have a field of view 100 times larger than that of the Hubble Space Telescope, is scheduled to be launched in October 2026. China plans to launch Chang'e 7 to explore the lunar south pole in late 2026.
This article documents expected notable spaceflight events during the year 2024. The first two modules of the Lunar Gateway will be launched in 2024. NASA plans to launch the Artemis 2 mission on the Space Launch System, sending astronauts around the moon on a ten day lunar flyby.
The universe will get smaller and smaller, galaxies will collide with each other, and all the matter in the universe will be scrunched up together. When the universe will once again be squeezed into an infinitely small space, time will end.
Andromeda–Milky Way collision
The merger will totally alter the night sky over Earth but will likely leave the solar system unharmed, according to NASA.
Earth is the only planet known to support life.
Humanity will, however, likely reach Mars within decades. China plans to start sending human crews to Mars in 2033 (opens in new tab), while NASA aims to send astronauts (opens in new tab) there by the late 2030s or early 2040s. Once humans get there, the next step could be to build a colony.
Our Milky Way is on a collision course with another spiral galaxy called Andromeda. Today Andromeda is visible as a speck of light in the night sky, but about 5 billion years from now, it will be tangled up with us. Our galaxy's spiral arms will disappear, and so will our supermassive black hole.
The Hubble Space Telescope has found not one or two, but as many as 6 galaxies that are dead, as far as their role of birthing stars is concerned. The Hubble Telescope was looking back in time to a period when the universe was some 3 billion years old.
When all of the stars in a galaxy die, and new ones are no longer forming, the galaxy itself ceases to exist. This occurs when all of the galaxy's gas is ejected, making it impossible for new stars to form.
The observable universe contains as many as 200 billion galaxies and, overall, as many as an estimated 1×1024 stars (more stars than all the grains of sand on planet Earth).
As their extended cosmic duet progresses, the pair will draw even closer together as surrounding swarms of stars and gas siphon away their orbital momentum. The authors predict that the dance will end in approximately 200 million years, when the two supermassive black holes at last fully merge to become one.