What is space and space-time? How spacious or big is it?

What is Space and space-time? Space is something, that looks like nothing, but has some hidden characteristics in it, which is as real as all the stuff in the universe that we can see in the night sky or even on the Earth.

It is the three-dimensional boundless entity of the universe. It consists of heavenly bodies like stars, galaxies, black holes, etc. But modern physicists define by considering the 3D space with 1-Dimension of time called space-time. It is the four-dimensional boundless extent of the universe. It is the hidden structure of the universe and is the active incredible dynamic medium. The force that connects our universe is called space-time.

image of the night sky (stars, Milky Way galaxy band, and space stuff) and Space-time

Contents in this article:

Where does Space begin?

view of the Earth atmosphere from space

Whenever we stare up to the night sky, we can see the moon, the planets and the stars, etc. and these are all one little portion of Space. But, here is a question, Where exactly does the ” Space” begin?

In the most general way, we define that space begins, where the Earth’s atmosphere ends or becomes so thin(which is neglected), and also the Earth’s gravitational pull becomes weak(i.e.neglected) too. But, again the question arises here, Where exactly does the atmosphere end?

According to Theodore Von Karman. He calculated and defined the boundary of the earth’s atmosphere and Outer space and called it a Karman line. Karman line is an imaginary line that separates the earth’s atmosphere and Outer space, which is at an altitude of 100 km(62 miles) above the sea level of Earth.

But according to NASA “there is no hard-definable point, where space begins from the perspective of pure physical sciences. The atmosphere decreases gradually as we move higher in altitude.”

The mystery of Space and Space-time

Space is the biggest mystery or unanswered question in science. Despite the name, it is not empty at all. Space itself is something. It is a dynamically active medium or an active player in the game of life, and it underpins the reality and time together to be called space-time. Space-time is what the universe really is. We can neither see nor touch nor feel it, but without space-time, we wouldn’t be here. To understand the concept of space-time, we have to think from the very beginning, that is from the Big-Bang.

Space-time has been active since the very beginning of the universe, and it’s the key to the evolution of everything. If we are to understand the history of the universe, we’ll have to understand space and time. In actual the story of space-time is the story of the universe. Our entire universe was born in the Big-Bang.

The Big-Bang was the instantaneous moment that everything was created merely from nothing. And the very definition of the moment of the Big-Bang is the creation of space-time at that instant. Moreover, space and time were the entities that were flying in all the directions where space got expanded by itself. Though the Universe didn’t expand evenly, the tiny speck of energy and space-time materializes from nowhere to expand suddenly.

Exploration of Space

Space exploration is using astronomy and space technology to explore outer space. It is the greatest adventure that humanity could have ever invoked. It’s an inspirational and interesting thing which is important too. We have seen how human has explored the space until now. Right from the human walk on the moon to spacewalk by cosmonauts and astronauts. We, humans, have also built an International Space Station(ISS) for research purposes. Satellites are injected into different orbit for different purposes by launch vehicles. These satellites are being used for earth observation, remote sensing, communication, etc. Moreover, Space shuttle crews are being used to carry astronauts to space and bring back safely to the earth.

We, humans, have also launched High vision telescopes into the space like Hubble Space Telescope, X-Ray telescopes, etc into the space for observatory purposes which has been enhancing our knowledge further. These telescopes are launched into particular orbits based on their purposes which shall work 24/7 and transmit data to Earth.

Did you know: The last time that all humans were on Earth together was on 2nd Nov of 2000. Since then, at least 2 of them have been working aboard in ISS.

Future missions

There have been numerous missions set and the most prominent one for the early decade is the launch of James Webb Telescope, which is going to be more powerful than any telescope launched till date. Russian space agency Roscosmos has partnered with Space adventures to bring about space trips for laymen and turn ISS into a hotel. ISRO(Indian Space Research Organisation) has planned to send manned spacecraft.

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