On July 11 of this year, NASA's James Webb Space Telescope (JWST) created history by sending a star-studded image of space. This is the deepest picture of the universe ever taken.
In addition to being able to look at the farthest reaches of the universe compared to other telescopes, the Webb telescope has another amazing ability. That is, this telescope can see more of the past than other telescopes.
The Webb Telescope can also capture some of the early scenes of the universe. It is able to observe how the planets and stars were about 13.5 billion or 13.5 billion years ago.
But how is this possible? How can a machine look 'into the past? The answer is, it is not magic but simply the nature of light.
'Telescopes can be time machines. Staring into space is like looking back in time,' NASA scientists explain on the Web Telescope website. 'It sounds like magic, but it's actually quite simple: it takes time for light to travel across the vast expanses of space to reach us.'
From the light of the mobile phone in our hands to the light of a star shining brightly in the night sky - all visible light takes time to reach our eyes. The good thing is that light can travel from one place to another very quickly. Light travels a distance of about three lakh kilometers every single second. That's why we don't feel the time when the light reaches our eyes from the mobile phone or the electric lamp of the house.
But when we look at an object hundreds of millions or billions of miles away, the light we see has traveled a long way through space to reach our eyes. And most of the objects we see in the night sky are located at a distance of hundreds of millions or billions of kilometers from Earth.
Let's think about the sun. The only star in our solar system is located at an average distance of 150 million (15 crores) kilometers from Earth. It takes about eight minutes and 20 seconds for light to reach Earth from the Sun. So when you look at the sun (but you should never look at the sun with your naked eyes), the sun you see is actually the sun eight minutes ago.
That means you have to wait another eight minutes to see what the sun looks like at your current moment. That is, to put it another way when you look at the sun, you are actually looking eight minutes into the past.
The speed of light is so important in astronomy that scientists use light years instead of miles or kilometers to measure great distances in space. The distance that light can travel in a single year is called one light year. This distance is about 9.46 trillion kilometers. For example, Earth's distance from the equator is about 323 light years. That is when you see the fixed star in the sky, the light of that star caught in your eyes is basically the old light of more than 300 years.
So, you don't have to spend money to buy a telescope to see the past. You can see it with the naked eye. But to look into the truly distant past, scientists need telescopes like JWST. This past could be as far back as the birth of our universe.
All kinds of light but we cannot see with our eyes. The light that can be seen with the naked eye is called visible light. One of the invisible lights is infrared light. Although this abalone light is invisible to the human eye, the web telescope can detect its wavelength.
Many other things, including humans, emit heat as latent energy. Although it cannot be seen with the naked eye, it is possible to find even the most mysterious objects in the universe using concave wavelengths if the right instruments and techniques are used.
This is because, compared to visible light, cosmic radiation can travel through the dense, dusty regions of space without being scattered or absorbed. Visible light from distant stars and galaxies cannot escape the dust cloud of space. But because optical light can easily pass through such obstacles, the Web telescope can use to image distant objects.
One of the most powerful features of the James Webb Telescope is its ability to detect infrared light. Thanks to this technology, the telescope can also observe the light emitted by the oldest stars and galaxies 13 billion years ago.
And this is how the Webb telescope took the famous picture of the deep universe last July. And by adopting this process, the telescope built at a cost of 10 billion dollars will search further into the past. It can also take pictures of what stars and galaxies looked like hundreds of millions of years after the Big Bang.
The stars that the web will photograph from the past are very likely to have become dead stars by now. But if their emitted light travels through the finite yet vast regions of space and is captured by our telescopes, we will be able to travel back in time with our mortal eyes.