> Making petrol engines 1% more fuel-efficient would be massive. Increasing the conversion rate of online ads by 1% could make you very, very rich indeed. Good

> Making petrol engines 1% more fuel-efficient would be massive. Increasing the conversion rate of online ads by 1% could make you very, very rich indeed. Good advice for AI probably; bad advice in other fields. It's good advice in every field. Most improvements have a cost. If you make engines 1% more efficient but 5% more expensive no one will care. Heck electric engines are wildly more efficient (80-95%) compared to combustion engines (20-35%), not to mention far simpler, and we can hardly get people to switch. Even immense improvements can be hard to roll out. Don't work on marginal gains. Any minor problem or inconvenience will wipe them out and all your time and effort will be worth nothing. Let people who are paid by companies do that. If you're going to do a PhD focus on something that could be big. Whenever students suggest a project I always start by asking what the upside is: what if we massively succeed?