Analysis of The Physics Concepts of Interstellar

Kip Thorne is an American theoretical physicist, known for his work on gravitational physics and astrophysics. He was the Feynman Professor of Theoretical Physics at the California Institute of Technology. And is one of the world's leading experts on the astrophysical implications of Einstein's general theory of relativity. He continues to do scientific research and scientific consulting, most notably for the Christopher Nolan film Interstellar, Kip Thorne was an executive producer for Interstellar

Thornes role as the scientific consultant for the film was to ensure the portrayals of the wormholes and relativity were as accurate as possible. Thorne worked out the equations that enabled tracing of bundled light rays as they travelled through a wormhole or around a black hole, this means what you see in Interstellar is based on Einstein’s general relativity equations.

Black Holes

This is the image of the black hole that was created for the Movie, they called this black hole ‘Gargantua’. This image was the work of around 30 people and thousands of computers for over a year. This black hole simulation is of exceptional accuracy, and very similar in many ways to the image we have recently captured of a black hole.

How it was made?

The group at ‘Double Negative’ created a new piece of software, called the ‘Double Negative Gravitational Renderer’. They used this software to solve the equations for ray-bundle propagation. The resolution of the software was so high that the team was able to observe and study the area around the event horizon. Gargantua was spinning at near the speed of light, using the ‘Double Negative Gravitational Renderer’, the team was able to observe that spacetime distorted into shapes never seen before. This led to the publication of scientific papers on the effect the black hole had on spacetime.

While the movies rendition of Gargantua is highly accurate, the final version, that wasn’t used in the movie, takes into account the rotational forces that would be created as the black hole spins.

The black hole that was created by Kip Thorne for the movie but deemed too confusing by Christopher Nolan, the director of Interstellar. This image was far too asymmetrical for Christopher Nolan’s liking. The image was asymmetrical due to the high speeds it was spinning at, dragging the light to one side. Nolan decided that it was too confusing for movie-goers.

Also, in this image they used individual rays of light instead of ray bundles of light, like what was used in the image that we saw used in the movie.

The image to the right is the first ever image captured of a black hole. The image was obtained by the Event Horizon Telescope observations of the centre of the galaxy M87. The image shows a bright orange-yellow ring, this light isn’t being produced by the black hole, but rather it is light that is being drawn towards the black hole, that is yet to be drawn into the event horizon, where light will no longer be able to be seen.

This isn’t a real image, but actually radio waves that were measured by scientists, then processed with a computer to build the image that we see.

A team formed to create the first image of a black hole. They created a network of telescopes known as the ‘Event Horizon Telescope’ (EHT). They endeavoured to improve upon the ‘Very Long Baseline Interferometry’ (VLBI). Each telescope used for the EHT had to be almost perfectly synchronized with the other telescopes to within a fraction of a millimetre using an atomic clock locked onto a GPS time standard.

The image we see is the work of a global network of radio/millimetre-wave telescopes joined together to create a planet sized telescope. The image we see is data patched together from all of these telescopes. The locations of the telescopes included Hawaii and Mexico, mountains in Arizona and the Spanish Sierra Nevada, the Chilean Atacama Desert, and Antarctica.

Evaluation

The image created by the team working on Interstellar had some similarities to the image captured by the EHT team, but also had differences. I believe the similarities outweigh the differences and believe that the portrayal of the black hole ‘Gargantua’ was accurate. The work of so many people on the team at Interstellar creating new pieces of equipment has paid off, to give a realistic but still viewable, look at a black hole, before a real one image of a black hole was available.

Features of a Black Hole

A black hole is formed in the event of a star of a large mass dying/exploding. These stars die due to them running out of hydrogen to form into helium. The stars will then begin to form the remaining helium into heavier elements, but these take more energy to be able to form. If the star doesn’t have the necessary energy to bond any elements into others, the star will begin to collapse in on itself as it doesn’t have the energy to keep itself the size it currently is. The dying star can form into a White Dwarf, Neutron Star or Black Hole. Only the largest of dying stars will form a black hole, when these large stars die they will cause supernovas.

A black hole is a singularity in space where the force of gravity is too strong for anything to escape, including light, caused by a warp in spacetime.

A black hole consists of a singularity that is surrounded by an event horizon. In this event horizon, the escape velocity is greater than the speed of light, and since the speed of the light is the fastest speed possible, it is impossible to escape a black hole. Outside this event horizon, the escape velocity is slower than the speed of light and therefore it is possible to escape.

Black holes can be in various sizes, each size will also have a different radius for its event horizon. The M87 black hole is about 6.5billion times the mass of the sun, whereas Gargantua was around 100 million times the mass of the sun. This means both these black holes are classified as ‘supermassive’ black holes. Scientific evidence suggests that every large galaxy will contain a ‘supermassive’ black hole.

In the Film

Within the film Interstellar, nearing the end of the movie, Cooper, played by Matthew McConaughey falls into the black hole, Gargantua.

After Cooper falls into Gargantua he is met with a 3-dimensional space of bookshelves. Each set of bookshelves represents a time in space, in Murph’s (Coopers daughter) room.

This space was created inside of the black hole by the future people of Earth, that survived due to Cooper saving the Earth. The Earth is saved by Cooper relaying Murph the information they need from inside the black hole, to solve the gravity equations that will allow the people of Earth, to escape Earth. TARS gets this information from the black hole and gives it to Coop in Morse, and Coop then set the Morse Code into the watch, by ticking the second hand on Murph’s watch. Cooper uses binary to relay the coordinates of NASA to himself.

They needed to solve these gravity equations to be able to more easily be able to leave the Earth’s atmosphere, to get the humans off of Earth.

The 3-dimensional world of bookshelves inside of the tesseract that Cooper is met with, is inside of the black hole. This 3-dimensional world is inside of a 5-dimensinal world created by the people of the future to allow the past people, being Cooper, to gain the required information from the black hole to solve the gravity equations, then give this information to Murph.

The physics in this scene are some of the least scientifically correct of the whole movie. Though the movie does recognise that the 3-dimensional world of bookshelves wasn’t a naturally occurring phenomena, but rather man made by an advanced species from the future. Using this plot feature, in our current society, no it is not possible, but by saying it was built by an advanced species that has a deeper understanding of the 5 dimensions, we can’t say it is impossible.

In Reality

In reality, if you were to fall into a black hole, there would be no way to escape. Light travels at the speed of light, which is 299 792 458 m/s, this is the fastest possible speed and it can’t escape. This is the speed limit of all matter in the universe as you would need an infinite amount of energy to speed another piece of matter up to the speed of light, this means there’s not enough energy in the universe to speed anything up to the speed of light. This means that if you were to fall into a black hole, you wouldn’t be able to escape. If you were in freefall, feet facing down the force of gravity as you reached closer to the centre of the black grows astronomically, but since you are in freefall, you are weightless and don’t feel this effect of gravity As you continue to fall and the effect of gravity becomes stronger, you begin to feel the effects of the gravity, because your feet are closer to the centre and therefore are experiencing more pull than the top half of your body. This difference in force begins to stretch your body, until this force becomes too strong, at which point, your body will become extruded by the gravity until you reach the centre of the black hole. This process is entitled spaghettification.

Comparison of Black Holes in Reality vs the Film

In Interstellar we see a speculative view of a black hole, on what could possibly happen in a futuristic world, but it is scientifically inaccurate. As Cooper fell into the black hole he was met with this 3 dimensional world of bookshelves, whereas in reality he would have been spaghettified as he began to draw closer to the centre of the black hole.

The physics in this scene are inaccurate, from Cooper and his ship not being spaghettified to Cooper being met with a 3-dimensional world of bookshelves inside of the black hole. This is the most inaccurate physics of the whole movie. While Christopher Nolan and Kip Thorne wanted to make this movie as scientifically accurate as possible, it was also an expensive movie to make. This means the movie needed to make money and to do this, they needed drama, and an intriguing plot. The used the unknown of what’s inside a black hole, to create their own speculative view, far from what is currently possibly with our understanding of black holes, to intrigue audiences.

Time Dilation

As the team of astronaut’s land on the planet in solar system that is millions of light years away, but the gravity of this planet is much stronger than that on Earth and ship. The astronauts were advised to spend as little time on this planet as possible as just 1 hour on this planet is 7 Earth years, as a result of gravitational time dilation

Light travels at speed ‘c’ in a vacuum (299 792 458 m/s). All gravity will bend spacetime, and the light will have to travel along this ‘bent’ space. This means that with stronger gravity comes more heavily curved lines, which will mean light has to take a further path, when there is stronger gravity. Using speed=distance/time, where ‘c’ is a constant, which we know from one of Einstein’s two postulates ‘speed of light c is a constant, independent of the relative motion of the source’. Since ‘c’ is a constant, then when the distance differs with two different strengths of gravity, the time must also change. This means time appears to be slower for objects in a strong gravitational field, when viewed from a frame of reference outside the influence of this gravitational field.

Well then what is the correct time then? Neither of them are ‘correct’ relative to both people, but relative to each person their own measured time is correct. This is a consequence of relativity, where time running in your own frame of reference is ‘correct’ only relative to you and is known as proper time. Other observers may measure a different duration of the same event, and their time is correct relative to their frame of reference.

The laws of motion must be the same for all observers, regardless of their motion, this means ‘time must slow down, such that the faster you move, the slower your clock runs’ relative to another clock. This means there are no absolute frames of reference. All measurements are relative to and dependant on the frame of reference the each set of measurements are taken from.

Time Dilation in the Film

Time dilation plays a huge role in the plot of the movie Interstellar, it first occurs on Miller’s planet. The time dilation on this planet is caused by the black hole Gargantua, the first mission/set of astronauts that was sent to Millers planet were killed on the planet were only on the planet for minutes, but due to time dilation on the planet, the people on Earth thought they were there for years and receiving years’ worth of data.

They send the second set of astronauts to Miller’s planet, this team then find that due to time dilation, each hour they spend on Millers planet will be 7 years on Earth. Due to this they attempt to spend as little time on Millers planet as possible, while still retrieving any information possible.

The gravity on Millers planet was 130% as strong as that on earth, due to the close proximity of Gargantua, the black hole. This causes them to attempt to evacuate the planet due to a large tidal wave that has been caused due to this close proximity to Gargantua. They fail to escape the planet in time, are hit by the tidal wave while inside their spaceship and spend much more time than anticipated on the planet. They ended up staying on this planet for around 3 hours, which translated into 23 years.

This is the best example the movie has of displaying time dilation.

Comparison of Time Dilation in Reality vs the Film

Time dilation is represented well in this movie, the numbers calculated by the characters in the movie all coincide with real world maths and equations. This means the time dilation follows real world science, since it follows real world equations. Kip Thorne did the scientific research for the movie’s time dilation aspects. He wanted to give the movie realistic physics, and this included realistic time dilation.

We on Earth always experience time dilation as long as we are moving, but since you have to travel at near the speed of light to notice any time dilation, and we on Earth travel at such small fractions of the speed of light, we don’t notice the dilation. This though isn’t the type of time dilation that is experienced in Interstellar, in Interstellar they experience gravitation time dilation, due to the black hole ‘Gargantua’, that is in close proximity to the astronauts for a large portion of the movie.

Worm Holes

The movie Interstellar is based in the near future and takes advantage of many ideas not yet possible in our modern times, but are theorised to be possible, an example of this is wormholes. Interstellar uses the idea that, because it is set in the future, ideas such as travelling through worm holes are possible. A wormhole is a tunnel through the fabric of space and time that could potentially allow rapid travel across space between two distant points. The movie uses this wormhole as a device to allow the team of astronauts to travel from near to Saturn, across the universe, to possibly habitable planets. The movie uses the idea of a wormhole correctly, but there are currently very strong indications that travel through a wormhole is forbidden by the laws of physics.

Wormholes allow something to travel from one place to another, faster than the speed of light would be able to travel to that point, by providing a shortcut.

Wormholes naturally emerge from the equations governing the theory of general relativity, but to keep these wormholes open, you need negative energy or negative mass. The amount of negative energy or negative mass required to keep a wormhole open for long enough to allow something to travel through it is currently impossible.

Potential Implications for the World

Wormholes hold some of the most potential implications for our world. Wormholes could possibly allow travel across the universe just like that seen in Interstellar. This would allow travel across the universe, much faster than ever previously possible.

People are driven to explore the surrounding worlds and galaxies and the only way to do so that we currently see, is to use wormholes to quickly travel long distances. Just like in Interstellar, exploring space may help us understand our view of the universe and how it could change the world around us.

Potential of Future Human Endeavours

In the movie Interstellar, Earth is becoming uninhabitable and they are using wormholes to travel to other planets that could possibly be habitable.

Wormholes are currently the only conceivable way of travelling long distances throughout the universe, this means if a situation were to arise where we needed to escape Earth and travel long distances in a short amount of time, wormholes may be the only answer.

Bibliography

• Lutz, O. (2019). How Scientists Captured the First Image of a Black Hole - Teachable Moments | NASA/JPL Edu. [online] NASA/JPL Edu. Available at: https://www.jpl.nasa.gov/edu/news/2019/4/19/how-scientists-captured-the-first-image-of-a-black-hole/ [Accessed 20 Jul. 2019].
• Smith, H. (2014). What Is a Black Hole?. [online] NASA. Available at: https://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-is-a-black-hole-58.html [Accessed 20 Jul. 2019].
• Germany, L. (n.d.). Black Hole | COSMOS. [online] Astronomy.swin.edu.au. Available at: http://astronomy.swin.edu.au/cosmos/B/Black+Hole [Accessed 21 Jul. 2019].
• Wendorf, M., Williams, M., Young, C. and Fuscaldo, D. (2019). The Interstellar Contributions of Kip Thorne. [online] Interestingengineering.com. Available at: https://interestingengineering.com/the-interstellar-contributions-of-kip-thorne [Accessed 21 Jul. 2019].
• Sinha, U. (n.d.). The Science of Interstellar. [online] Scienceofinterstellar.com. Available at: http://www.scienceofinterstellar.com/index.html [Accessed 22 Jul. 2019].
• Kennell, J. (2015). How Gravity Changes Time: The Effect Known as Gravitational Time Dilation. [online] The Science Explorer. Available at: http://thescienceexplorer.com/universe/how-gravity-changes-time-effect-known-gravitational-time-dilation [Accessed 22 Jul. 2019].
• Woo, M. (2014). Will we ever… travel in wormholes?. [online] Bbc.com. Available at: http://www.bbc.com/future/story/20140326-will-we-ever-travel-in-wormholes [Accessed 24 Jul. 2019].
• Ccswim.info. (2019). Images of Black Hole Spaghettification - #SpaceMood. [online] Available at: https://ccswim.info/space/black-hole-spaghettification.html [Accessed 23 Jul. 2019].
• News18. (2019). Interstellar Black Hole Image of Gargantua Was Not Too Far From Reality. [online] Available at: https://www.news18.com/news/tech/interstellar-black-hole-image-of-gargantua-was-not-too-far-from-reality-2099249.html [Accessed 21 Jul. 2019].
• Resnick, B. (2019). How to make sense of the black hole image, according to 2 astrophysicists. [online] Vox. Available at: https://www.vox.com/science-and-health/2019/4/11/18306110/first-image-black-hole-eht-event-horizon-singularity [Accessed 24 Jul. 2019].
• Aron, J. (2015). Interstellar's true black hole too confusing. [online] New Scientist. Available at: https://www.newscientist.com/article/dn26966-interstellars-true-black-hole-too-confusing/ [Accessed 25 Jul. 2019].