Do you mean a new discovery to come? If so then there are so many and because it is the future I don’t have to be limited by the current boundaries of science today.
I think the discovery of what dark matter and dark energy actually is will be a massive achievement as it will help us to understand so much more about the universe. The matter we know of, stars and planets account for 5% of the universe, dark matter ~27% and dark energy 68%.
But that will possibly be a more of historical importance about how universe came to be and whether the universe will carry on expanding forever or not. If we turn more towards home then I think the next greatest discovery will be the creation of a cold fusion reactor. Fusion is a process where hydrogen is fused into helium and it is what powers the sun. The creation of this form of energy will have massive implications for our energy use in the future. Firstly it is a clean source of power. It will also create a huge amount of power that will release us from our dependence on fossil fuels which are quickly running out.
At the moment they are building a reactor in France although they still have not yet solved the technology to get it to work so the next 10 years of construction is the time they have to get the theory to work in reality so they can turn the reactor on.
Great question! I’m not sure which discovery will mark the biggest turning point in science – it probably depends on who that turning point is for. Will it help more people, tell us more about the world we live in, or even give us access to live in other parts of the universe?
On a closely related topic, the recent Longitude Prize picked 6 key topics that we need to address soon: water, paralysis, food, flight, dementia and antibiotics. The public vote was revealed on The One Show last night, giving the £10 million prize to help find a solution to antibiotic resistance. Whilst seeing such huge public support for this is great for me working in infectious diseases, I wanted to point out the range of problems highlighted by the prize – a discovery can help us in many (possibly unexpected) ways, and so is difficult to predict.