I had a long trip home last night. All the way from a sunny Luton back to Chippenham. Thankfully I got home in time for bedtime with the kids. So we went on iplayer to find something to watch together. Horizon’s “Secrets of the Solar System” caught everyone’s interested and we settled down to watch.
Things started off well enough. The production quality was good. It captured the kids attention from the start with a clear simple narrative and great special effects. I was also learning new things. The idea of the Jupiter and Saturn forming at the point where water turns from liquid to ice is very compelling. It also explains why they grew so fast.
However it isn’t long before I’m starting to shout at the TV. First with the programmes central point. This is that the old clock-work view of the solar system needs replacing with a model where the planets move around. During this whole discussion there was no mention of the Three Body Problem.
This idea basically says that if you have two objects then their orbit around each other is stable. However you only have to add one more object into the mix and things get chaotic and unpredictable. The more objects you have the more chaos ensues.
Once you’ve got an understanding of the three-body problem then the question becomes how is our solar system so stable? When you look at the orbits of the 3 objects above then any thought the the early solar system came into being in the same stable configuration it is today is surely madness? Why didn’t the Horizon team tackle this subject? I’ve seen Brian Cox tackle the subject before and it isn’t hard to visualize.
Unfortunately things got worse. Next we had the Hot Jupiter discussion. At no point did Horizon mention Sampling Bias. We see Hot Jupiter type systems out there simply because these massive gas giants sitting close to their sun’s are easy to see. Do these solar systems look weird? You bet. What conclusion can we draw from that? At the extremes of possible solar system formation there are some pretty weird configurations.
As my 10 year old said. It all seems pretty random. Based on the chaotic orbits you can expect in any system with more than two bodies it seems impossible to predict how the final stable configuration is going to look like. Once our ability to see other systems improves perhaps we’ll find each configuration is unique. Just like our fingerprints.
So that takes us back to the original question. Why is our solar system so stable? Well that one again is simple. Because we’re here. Life needs a stable system that works perfectly for life. There is no mystery in that.