There's a limit to how much of the universe we can see. The observable universe
The observable universe
The observable universe is a ball-shaped region of the universe comprising all matter that can be observed from Earth or its space-based telescopes and exploratory probes at the present time, because the electromagnetic radiation from these objects has had time to reach the Solar System and Earth since the beginning of ...
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is finite in that it hasn't existed forever. It extends 46 billion light years in every direction from us. (While our universe is 13.8 billion years old, the observable universe reaches further since the universe is expanding).
Cosmologists aren't sure if the universe is infinitely big or just extremely large. To measure the universe, astronomers instead look at its curvature. The geometric curve on large scales of the universe tells us about its overall shape. If the universe is perfectly geometrically flat, then it can be infinite.
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.
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.
Thanks to dark energy and the accelerated expansion of the Universe, it's physically impossible to even reach all the way to the edge of today's observable Universe; we can only get a third of the way there at maximum.
After about one minute circulation effectively stops. The lack of oxygen to the brain renders you unconscious in less than 15 seconds, eventually killing you. "When the pressure gets very low there is just not enough oxygen.
The world as we know it has three dimensions of space—length, width and depth—and one dimension of time. But there's the mind-bending possibility that many more dimensions exist out there. According to string theory, one of the leading physics model of the last half century, the universe operates with 10 dimensions.
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). Typical galaxies range from dwarfs with as few as ten million (107) stars up to giants with one trillion (1012) stars.
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.
No, they don't believe there's an end to space. However, we can only see a certain volume of all that's out there. Since the universe is 13.8 billion years old, light from a galaxy more than 13.8 billion light-years away hasn't had time to reach us yet, so we have no way of knowing such a galaxy exists.
The Big Bang theory says that the universe came into being from a single, unimaginably hot and dense point (aka, a singularity) more than 13 billion years ago. It didn't occur in an already existing space. Rather, it initiated the expansion—and cooling—of space itself.
Our universe began with an explosion of space itself - the Big Bang. Starting from extremely high density and temperature, space expanded, the universe cooled, and the simplest elements formed. Gravity gradually drew matter together to form the first stars and the first galaxies.
The multiverse is a hypothetical group of multiple universes. Together, these universes are presumed to comprise everything that exists: the entirety of space, time, matter, energy, information, and the physical laws and constants that describe them.
According to NASA, time travel is possible, just not in the way you might expect. Albert Einstein's theory of relativity says time and motion are relative to each other, and nothing can go faster than the speed of light, which is 186,000 miles per second. Time travel happens through what's called “time dilation.”
Many religious persons, including many scientists, hold that God created the universe and the various processes driving physical and biological evolution and that these processes then resulted in the creation of galaxies, our solar system, and life on Earth.
Using data from NASA's Transiting Exoplanet Survey Satellite, scientists have identified an Earth-size world, called TOI 700 e, orbiting within the habitable zone of its star – the range of distances where liquid water could occur on a planet's surface.
Intergalactic distances are roughly a hundred-thousandfold (five orders of magnitude) greater than their interstellar counterparts. 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.
The things in our daily life have height, width and length. But for someone who's only known life in two dimensions, 3-D would be impossible to comprehend. And that, according to many researchers, is the reason we can't see the fourth dimension, or any other dimension beyond that.
We're looking back in time the further out we go because it takes time for light to travel to us. So the furthest out we can see is about 46.5 billion light years away, which is crazy, but it also means you can look back into the past and try to figure out how the universe formed, which again, is what cosmologists do.
Once civilian space travel starts, they will be guided by professional astronauts. These initial missions provide training opportunities for the space crew and companies. The first initial civilian space flight is planned for early 2022. Four people will fly to stay at the International Space Station for ten days.