Scientists reveal the simple way you can time travel
- READ MORE: Scientists say time travel is possible - and people have done it
For centuries, being able to travel back and forth in time has been one of humankind's greatest ambitions.
Depicted in films such as Back to the Future, Austin Powers and Interstellar, time travel often involves a fancy contraption effortlessly put together by boffins.
Even in BBC sitcom Blackadder, dimwitted Baldrick manages to assemble a working time machine out of some old wood and a fruit machine.
Of course, no one has demonstrated the kind of back-and-forth time travel seen in these classics.
But, that's not to say it's impossible.
Scientists say time travel is feasible, although you might need a space station, a plane and some atomic clocks to prove it.
However, the easiest way to time travel is simpler than you probably think – and it doesn't involve any fancy equipment.
So, what's the trick? Simply look up at the stars.
The closest star, Proxima Centauri, is 4.24 light-years away. A light-year is 9.44 trillion km, or 5.88 trillion miles. While this is an incredibly large distance, it pales in comparison to the most distant stars. Pictured, Proxima Centauri in an image from the Hubble Space Telescope. Proxima Centauri is not visible to the naked eye
In Christopher Nolan's film Interstellar (pictured), time travel is achieved by flying an elaborate spaceship close to a black hole
When you look up at the stars, you're looking at suns from other solar systems, most of which have their own set of planets orbiting around them.
The most distant stars are located billions of light years away – meaning the light from them has been travelling for billions of years to reach our eyes.
'The scale of the cosmos is so vast that even the fastest thing in the universe – light – has to travel for very long times to cross it,' Dr Michael Boyle, astronomer at Cornell University in New York, told MailOnline.
'Light from the most distant individual stars we can see with the naked eye has been traveling for thousands of years, or billions of years for the most distant stars we've seen in telescopes.'
So when we see a star in the sky, we are actually seeing a snapshot of what it looked like thousands of years ago, not how it is now.
Essentially, by looking up at the stars we are transporting ourselves thousands of years into the distant past.
And it may seem unbelievable, but because a star's light has been travelling for such a long time, by the time it reaches us that star may not even exist anymore.
'The stars that gave us that light have gone on living their lives, possibly using up all their fuel and dying long before their light got to us,' said Dr Boyle.
A star system visible to the naked eye, Eta Carinae (made up of two stars in orbit around each other) is 7,500 light years away
When you look up at the stars, you're looking at suns from other solar systems , most of which have their own set of planets orbiting around them. This picture shows the location of Proxima Centauri in the southern skies over the La Silla Observatory in Chile
Just like we can only see objects because light has reflected off them, we can only see stars because light has traveled from them, through the vast galaxy and into our eyes.
'This light carries the information of what the star looked like at the moment when the light was created,' Professor Christopher Baird, physicist at West Texas A&M University, told MailOnline.
As an example, a bright star called Deneb can be seen in the constellation of Cygnus, a prominent cross-shaped constellation in the northern sky.
Deneb is an estimated 2,600 light years away, meaning its light has travelled for 2,600 years to reach us.
When light from Deneb started its journey, it was the 6th century BC – around the same time the Roman monarchy was overthrown and the Hanging Gardens of Babylon were built.
Another star system visible to the naked eye, Eta Carinae (made up of two stars in orbit around each other), which is 7,500 light years away.
'Eta Carinae, at 7,500 years, corresponds to when humans were domesticating our most important crops, like barley, wheat, and rice,' said Dr Boyle.
Meanwhile, light from the Andromeda Galaxy – which has more than 1 trillion stars and is the most distant thing we can see with the naked eye – left 2.5 million years ago.
Our sun (pictured) beams its light out over the Milky Way galaxy just like the stars we see when we look up at night
Deneb is the brightest star in the constellation of Cygnus thought to be 2,600 light-years away
'2.5 million years ago is the beginning of the last Ice Age, and when the very first ancient humans (homo habilis) were still just developing ,' Dr Boyle added.
'While we can't see any individual star in the galaxy, its trillion or so stars combine to make a large fuzzy patch that's wider than the moon, and easy to see on a reasonably dark night.'
According to Professor Baird, there's no way for us to exactly know the present state of a distant star – meaning the ones we see may or may not still exist.
'There are different ways that a star can cease to exist; it can merge with a black hole, be ripped apart by the strong gravitational forces of a neutron star or black hole, run out of fuel and go dark, or can explode as a supernova,' Professor Baird said.
Earendel, the farthest star ever detected, is 28 billion light years away – although due to a quirk of our ever-expanding universe its light has travelled for 13 billion years to reach us.
Detected by the Hubble Space Telescope in 2022, Earendel is 'surely long gone', because a star's typical lifetime is much less than this.
'It must have been a very bright star to be seen from so far away, and therefore must have had a very short life,' Dr Boyle told MailOnline.
'But we're seeing the star as it was billions of years ago, which is probably much longer than its lifetime.'
The Andromeda Galaxy is approximately 2.5 million light-years from Earth and the nearest large galaxy to our galaxy, the Milky Way
Perhaps most amazingly, lifeforms in other galaxies billions of light years away could be looking at our sun through their own telescopes.
Potentially, if an alien 65 million light years away was looking at Earth through a telescope that's powerful enough, they could be seeing the dinosaurs.
If we were only able to create telescopes adept enough, we could – hypothetically – get a detailed look back in time at other words too.
And although it may be the stuff of sci-fi for now, if only we could reach these distant worlds we could look back at planet in different periods of its history too.
