INSIDE THE SKY AT NIGHT

September's Sky at Night episode tackled the Hubble constant. George Dransfield considers how some of the cornerstones of science aren't as rock-solid as we thought

- George Dransfield

If there's one thing I love, it's a misnomer. Shooting stars, planetary nebulae, guinea pigs... none of them does what it says on the tin. Another great example is the term 'physical constant'. These are quantities that are so fundamental that they have the same value throughout the Universe, and have done since the dawn of time. Or so we think! Buckle up, readers: for one night only, I'm activating my long-dormant Physics Teacher Mode.

I have tremendously fond memories of my teaching days, and one particularly endearing thing my A-Level students did was show off to one another (and to me) how many physical constants they had memorised. I often pointed out that this was a legitimately pointless skill; after all, professional physicists have access to the internet. But still, they delighted in reciting the value of elementary charge, for instance, and groaned whenever I introduced yet another constant to add to the list.

Now, elementary charge - that is, the amount of charge on a proton - is a fundamental constant of nature. As in, every single proton in existence in the Universe, throughout all of time and space, has the exact same amount of charge. Forgive me if I nerd out about this point for a moment, but isn't it wild that we know this? I think so, at least.

September's episode of