Although a seemingly simple movie about an emotional separation of a father and a daughter, Interstellar packed some serious theoretical physics in it. Some reviews focused on the emotional part and called the theoretical physics jargon just a way to create a story, but my mind was fixated on that “jargon”. It’s a pity that not everyone understands the implications of theoretical physics. Day in and day out we follow the same routine, and deal with daily life issues, work issues, family, friends and everything around it. And just 50 miles above us, starts nothingness, with smatterings of matter here and there, but mostly nothing. All the stuff we deal with on a daily basis start to become really insignificant as we imagine ourselves looking down at Earth. I have been hooked on to the physics of the Universe ever since I read ‘A Brief History of Time’. I literally have my head up in space when I ponder over these ideas that mathematics and physics have given birth to. I am in no way a physicist (although I do rethink my profession time to time) and neither do I write movie reviews (heck I don’t even write for long periods of time). But I am a serious theoretical physics fan, and when a movie like this comes along, my mind goes berserk soaking up the ideas re-created on-screen that it has been desperately trying to visualize.

**Warning: The last time I was this excited about a movie was when the Tintin movie came out.*

I am not telling you the story (if you haven’t seen it yet, why the fuck are you wasting your time reading this!), no spoilers and absolutely no reviews. This is probably a feeble attempt at summarising the ideas that were used in the movie. Let’s go.

Let’s start with a **singularity**. In simple English, a singularity is a point, a state, fact or quality of being singular, unique. There has been debate about the exact definition of a singularity in terms of General Relativity, but it is that one single point, which is infinitesimally small and where all the laws of physics breakdown. Our universe was a singularity at some point in time (13 billion years ago, to be precise). We know that the universe is expanding, and if we play the expansion of the universe in rewind, we can visualize everything contracting and coming back together, until it finally all just comes down to a point. A **singularity**. An explosion in this singularity (The Big Bang) gave birth to our universe and everything inside it. At the centre of a black hole is a singularity, a dying star that collapses on its own and gives birth to immense gravity. So you see, a singularity in the terms of Relativity is probably where all the answers to the mysteries of our universe lie.

Next up is the **horizon**. No, this isn’t your beautiful Sun setting, where the sky and the earth meet. What they mean when they say horizon, is the **event horizon**. An event horizon is the very edge of the black hole, where the gravitational pull is so strong that it makes escape impossible. Even if there was any light beyond the event horizon, it would never reach the observer. If an observer sees an object approaching the event horizon, he will never see it actually pass through the event horizon, he will see the object fall slower and slower. This is because light from the object is having a tougher time escaping the pull of the black hole. Basically, it’s “the point of no return”. And since no light can escape a black hole, the observer will never know when the object crosses the event horizon, just constantly seeing a dot image of the object hovering over the black hole.

**Time Dilation**. Stuff responsible for perhaps the most intense scene in the movie. Brand and Coop return to the *Endurance *after an hour’s trip to Miller’s planet, and realise that more than 23 Earth-years have passed since they left *Endurance*. **Time dilation** is real stuff. It happens to astronauts orbiting Earth on ISS, they age about 0.007 seconds slower than the people on Earth. A miniscule amount, because their orbiting speed is about 7.7 km/s, and for time dilation effects to be actually perceivable, their speeds should be close to 300,000 km/s, or the speed of light. It’s interesting to note that current GPS satellites have to take into the effects of time dilation and actually adjust their clocks to match Earth times. Experiments involving clocks being flown away from Earth to measure the effects of relativity have been successful in reporting time dilation results within 4% of the predictions of relativity. Relativity is for real people!

Gravity has been explained due to the effects of warping of the **fabric of space-time**. Any large object sufficiently manages to bend the fabric of space-time, creating a dent, and hence attracting other lighter bodies. Imagine a larger fabric stretched out, and you place a ball in it. The fabric will dent where the ball is. Place a heavier ball, and you will have a larger dent. And now, if you place another lighter ball, it will roll towards the heavier ball due to the slope in the fabric. Think of the fabric as the **fabric of space-time **and the heavy ball as a star, or any other heavenly body. There’s gravitational attraction for you! Gravity doesn’t seem so mysterious now, right?

Another notion used extensively, and a major reason the protagonists land themselves in the situation, is **wormholes**. A wormhole, officially known as the **Einstein–Rosen Bridge**, is a theoretical bend in space-time that connects two extremely distant points. Travelling through it will allow the intrepid explorer to reach the other spot in an insanely short amount of time, as compared to if she took the direct route. Points that would take hundreds of years to traverse could be reached within hours or minutes. Wormholes have never been observed directly, but the equations of general relativity have valid solutions that contain wormholes. This bit of interstellar physics just blows my mind! If we had the technology to create one and explore it, I would definitely want to be on one of those unimaginable trips.

The last one I want to mention is **Einstein’s Paradox**. While not directly mentioned in the movie, the outcome of the protagonists in the movie is a result of **Einstein’s Paradox, **which in turn is a result of time dilation. It is a thought experiment in special relativity involving twins which says that if one of the twin were to leave Earth and go on an epic journey across the universe in a high-speed rocket, when he returns to earth, his twin on earth would have aged more than the twin who went on the journey. Time would have run slower for the twin on the journey, and so would his aging functions. People have some considerable difficulty grasping this notion, but we must remember that time controls everything. Relativity has proven the effects of immense speed and immense gravity on stretching and delaying time. We don’t have the technology to undergo interstellar travel and actually prove it, but I’m sure it would be dream come true for numerous physics enthusiasts out there to practically experience the implications of interstellar travel.

Well, that’s interstellar physics for you. Fascinatingly inconceivable, yet complete with mathematical proofs. I wish I could see the evidence for these concepts that the equations so robustly support. I wish I could be one of those crazy people to take a journey into the unknown!