*Jonno R asked the Naked Scientists:* Hi Dr. Chris, John here from London.

How accurate are mathematical projections about the distant future of the universe? Is it really going to happen or is it all just fun with maths?

Originally I had a few questions about the heat death of the universe. How big would the universe be at the point just before everything stops? And would the question of size be relevant at the point just after? And if the dead universe is just energy with no time, mass or dimension, is that not a singularity?

The thing is that as we don't understand dark matter and energy, is it even worth asking these sort of questions? Surely mathematical projections into the past and future become more inaccurate the further you go If the model isn't complete.

Is it unfair to say that scientists should stop frightening us with projections about the unobservable until they fully understand the observable? I'm only 50 and so far I've been told that I would float in circles forever. Then it was decided that I was going to be crunched up small. Now suddenly I'm going to fly apart into little bits.

Great podcast, thanks.

John Raab.

*What do you think?*