If the 1st Law of Thermodynamics is true how could the Universe begin from nothing?

To answer this question we need to remember that nothing is a global term and not a local one. Vacuum states exist where there is no matter or energy (they have maximum entropy) and they are, as we can understand them, empty. Those are their global characteristics. In those realities the local situation is different, you can have local fluctuation of Entropy, which will create energy and matter, and a leading hypothesis is that the Universe was born from one of those fluctuations.Our current understanding of the Universe doesn’t allow us to probe anything before the Big Bang so this is mere speculation.

Now, the Laws of Thermodynamics are true! But they’re often misused because people don’t understand all the requirements. The first law is just a different way of discussing the conservation of Energy and can be expressed as: “The total energy of an isolated system does not change. In an isolated system energy cannot be created or destroyed“. The keywords here are ‘isolated system’. As far as we know the Universe is an isolated system, but our physics is valid up to an instant after the Big Bang. Thermodynamics might not have been valid at the very beginning, but since then it has been rock solid.

Image Credit: Stephen van Vuuren