A ‘lifestyle’ website, which shares the first three letters of its name with a certain internet search engine and is fronted by a recently ‘consciously uncoupled’ actress, has, just this year, felt the need to speak out on ‘The mysteries of the thyroid’.

The expert voice they rely on is a self-proclaimed ‘medical medium’ who (and I quote) ‘can scan the body from afar, and with the help of “Spirit” explain what ails or does not’. Perhaps this, at long last, explains how the trusty medical tricorder of Star Trek’s Dr ‘Bones’ McCoy actually works!

Millions of people visit this particular website to buy lifestyle items (jade eggs for your ‘yoni’ anyone?) and obtain health ‘advice’. Yet, while this may be one high-profile example, the darker recesses of the internet are populated with many other such sites.

The astrophysicist Neil deGrasse Tyson famously said about science, ‘It’s true whether or not you believe in it. That’s why it works.’ Why, then, do so many people believe what clearly are, at least to us scientists, alternative facts?

Ignorance and stupidity are answers that slip off the lips. However, it is easy to forget that while we are all experts in our own little patch of intellectual or technical real-estate, we all have ‘faith’ and believe in a multitude of things that we understand little about every single day.

How many of us truly understand how the brakes in our car work, or what keeps planes in the air? Are you qualified to assess the primary climate change data? Yet we all drive or fly, and (most of us anyway) believe that humans have and continue to play a major role in global warming. We trust that other experts are doing their job (as we are doing ours) and getting things right and, as a result, society functions.

The problem is, how does one tell an actual expert from a fake in this ‘post-truth’ era? If you are of an orange hue and tweet nonsense in the early hours, many people will believe you because surely, as the ‘leader of the free world’, you will have access to the relevant information? If you are a ‘doctor’ claiming that vaccines cause autism, surely you know what you are talking about?

The only way to combat this degradation of the value of truth is to be, as scientists, passionate about the truth. We have to find out the truth, tell the truth and call out untruths whenever and wherever we can.

Giles Yeo, Science Committee correspondent

Twitter: @GilesYeo