Interstellar, a look at some of the scientific principles


Wow, what a film! Well at least I enjoyed it, I don’t know about you guys. There’s been a lot of talk about the science behind the film  and a lot of discussions about how accurate it all was. I make no claims to be qualified to make a judgement on how true any of it could be, but, if you will indulge me for a few minutes, I would like to look at the scientific principles underpinning the story and give my own humble opinions on them.

The two big stars, no puns intended, are of course the wormhole and the black hole, Gargantua.

Lets look at these in order of when we meet them in the film.

The wormhole. This is an artificially created shortcut from our part of our Universe to another part of our Universe. This is actually possible, at least in theory. In fact it all goes back to Einstein and Relativity. To cut a long explanation short, if we imagine that the space-time of our Universe is a flat sheet, then it  doesn’t matter if we are talking about a trip to another galaxy or going to the shops, the route from A to B always follows the surface of the flat sheet. If we then imaging that this flat sheet is actually curved or folded over on itself, then by “tunneling” straight through from one side to another, we can create a short cut to somewhere else. Here’s a picture to show how it works-Wormhole, conceptual artwork

Just remember that this is a 2 D picture to show it in a way our limited brains can understand. In reality it would be in 3 D and would therefore appear to be a sphere although it would actually be a 3 dimensional hole in our space-time.

All our theoretical models and experimental data points to this being possible in practice. The problem is that we don’t know how to dig such a tunnel. We know from calculations that it would require a vast amount of energy, and I mean really huge, but how to channel that energy, what to actually do with it and what kind of “machines” that this would require is way beyond us, for now. Anyway, this is a film so we must accept that somebody, advanced aliens or our own distant descendants, have worked out the “how to” bit although why they should put it out by Saturn so it takes us 2 years to get to it I don’t understand but let’s leave it at that for now, maybe someone out there has a suggestion such as radiation dangerous to life on Earth?

The next on our list is Gargantua, the Supermassive Black Hole. Cleverer minds than mine have calculated that it is possible for a planet to orbit a SMBH in a perfectly circular orbit at a safe distance. Fine so far, and if one planet can do this then so can multiple planets at varying distances. My only question here is how did they get there? If they are left overs from the progenitor star’s planetary system then they should have been vaporised when the went supernova and created the black hole. If they were captured later, then they would have come in at an angle and this would likely give elliptical orbits which probably wouldn’t be stable in the long-term. The last possibility is that they coalesced from the debris left over from the supernova and such planets have been located orbiting a neutron star,

Both on Earth and everywhere else it’s all about location, location, location, and this is a bad location. Either your planet gets almost no energy from the neutron star, or it is in the way of the high energy beams and gets spit-roasted every few nano seconds.


Ok, so the black hole planet scenario is a possibility. Next question then is how they get the energy to maintain a reasonable temperature. Well the black hole is busy devouring matter which accumulates around the black hole in an accretion disc. As stuff gets closer to the black hole’s event horizon, it moves faster and faster reaching millions, even billions of degrees. As you can imagine, there is plenty of heat and light being radiated out to any planets nearby. The only trouble with this is that there is a lot of other kinds of radiation as well, x-rays and gamma rays which aren’t what you want to be bathing a planet you want to live on. Basically they are deadly so they are bad news. The other problem is that the planets closest to Gargantua would be pummeled by matter on its way in towards the black hole and this too is bad news.

The images of Gargantua are, on the other hand, both spectacular and accurate. The accretion disc is just that, a disc, but due to the relativistic effects of extreme gravity, the image, in fact the light itself, is bent around the event horizon in an effect called gravitational lensing and this is good news, at least for us here and now as it allows us to see objects that would otherwise but too distant to see. Actually to be completely accurate, the light from the disc isn’t actually bent, it travels in a straight line, but space-time itself is  distorted out of shape and light just follows a straight line in, bent, space.

The film has taken a few liberties with scientific accuracy for the sake of making an entertaining film. For example the tsunamis on the water world, if these are tidal then they would occur every time that side of the planet faced Gargantua but we saw no night time while they were there. and some details of the ice world like, “It has no surface”, it must have some form of surface somewhere, unless it is a gas giant and that creates even more credibility problems but never mind.

One thing that does bother me is the idea of transporting the whole of Earth’s population to another planet. How does one move 7 to 10 billion people? No spoilers here for those who haven’t seen the film yet so I will let that point rest but any film, book or anything which contemplates moving us all to another planet has a logistics problem, ’nuff said.

Finally, the end of the film. Without risking spoilers I will just say that here we have to just accept that for a civilization thousands or millions of years ahead of us, some things a possible that we would consider, well. science fiction. Also, why they would want to help a bunch of jerks who have ruined their own planet, by giving them a new one to ruin is open to question. And if “they” are in fact our own distant descendants, then we have a paradox. The human race survives because it’s descendants come back and rescue it. But it can’t have developed the technology to do that if it didn’t get help to survive and so on in self contradicting circles.

I hope this doesn’t sound like I didn’t like the film, I  did, a lot! The space scenes were especially beautiful and lifelike, probably the best I have ever seen as they were based on real footage from the ISS, shuttles etc, at least in terms of the appearance  and I found them truly convincing.

So get out there and see interstellar if you haven’t done so yet, and if you have then let’s hear from you.


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