We Are Actually Looking into the Past When We Look At Stars
The idea behind time travel has been a fascinating subject of discussion for generations. We see time travel in TV shows, movies, works of fiction, etc., in which some state-of-the-art machines are depicted that take you into the past or the future. Well, that isn’t really plausible, right? Everyone believes that time travelling is a myth. The past of see, past of do, and past of look are concepts that people might not be able to experience, at least not now.
Imagine the things that we could do if we could travel into the future. Wars could be prevented, vaccines for viruses could be invented, and millions of lives could be saved. Not to mention that we would be able to see our near and dear ones and their fates in the future. The concept, however mind-boggling and interesting, is somewhat confusing as well.
The Night Sky filled with Stars
Also Read: Can We Reach the End of Space?
So, what if we told you that you are actually time travelling every single day? Yes, every single time, we are actually looking into the past when we look at stars. Sounds unbelievable, right? Well, in this article, we will try to explain the details so that you can comprehend how time travel takes place in the real world.
The Speed of Light and the Sun
When we say that we are time travelling, we don’t necessarily mean that you can hop into your car one day and just zoom into your future or past. Not the time travel that we are explaining here is pretty different and something that you are actually experiencing every single day or night.
We know that light tends to travel about 300000 km/sec. The speed is incredibly fast, and hence when you switch on your light bulb in the room, there is instant light. So, you don’t necessarily have to wait for the light to see it.
However, when we talk about the sun and the speed of light, things tend to change a little bit. The distance between the Sun and our Earth is approximately 120 million kilometres. So, light from the Sun has to actually cover this distance in order to reach our Earth and lighten up the sky. So, the entire journey of the Sun's rays to reach Earth takes about 8 minutes. Even with the extremely fast speed of light, it reaches the Earth 8 minutes late.
How Does This Relates To Time Travel?
When you are looking at the Sun, you aren’t really looking at the present version of the sun but the version that it was 8 minutes ago. How does this relate to time travel, one might ask? Well, by the time you see the sunlight, we have already advanced 8 mins into the future. So, the Sun that you are seeing is actually the past version of the Sun. So, you are technically viewing the past. Sounds extremely interesting, right?
Looking at Stars: Is It Looking Back in Time?
When you are gazing at the night sky full of shimmering stars, you often admire their beauty, yet you are completely unaware of the fact that these sparkly things in the sky don’t even exist right now. By the same concept as the Sun’s light, it is evident that looking at stars is a look back in time.
For instance, Sirius is a bright star that is about 8.6 light years away from the Earth. Simply put, one light year is equal to about 9 trillion Kilometres. So, by the time the light from the stars actually enters your eye in the present time, those stars have already gone. The Sirius star that you see today is actually the one that was 8.6 years ago!
There are so many celestial bodies and stars that are far from the Earth. Hence, when we look at these stars through the telescope, we are actually looking at the past.
What Would Aliens See When Looking At Our Earth?
One of the most common questions about time travel is what alien telescopes would see looking at the Earth. Most people have made the statement that if an alien is looking at us from 65 million light-years away, they would see dinosaurs when they use the telescope to look at the Earth. So, is this correct? Well, technically, yes. Let us see how.
The last species of dinosaurs known to humankind went extinct about 65 million years back. Hence, when the light left the Earth, it was actually 65 million light years away. Take the example of the galaxy NGC 4845. It is located approximately 65 million light years away from our planet. Hence, we are able to see the galaxy as it was 65 million years ago. So, don’t you think it would be the other way around if they could also see us?
If there were some intelligent beings in that galaxy in possession of a highly powerful telescope that they could use to look at the Earth, they would see our Earth as it was 65 million years ago. So, there is quite a high possibility that they would see dinosaurs when looking at the Earth from their planet.
Conclusion
In this article, we have already discussed all the theoretical possibilities related to time travel and the speed of light. However, are these possibilities even real? How can we know about the past? Well, the questions are many, and unfortunately, there are no practical answers. The universe is a vast mass made of matter, dark matter, and much more.
Some calculations by scientists revealed that the Miky Way Galaxy is about 100000 million light-years away, and there are other galaxies larger than ours. So, to look at something that is about 65 million light-years away, the aliens would definitely need a really big and powerful telescope. So, as much as time travel or looking into the past seems interesting, there are no practical implications to the concept yet.
