When the universe expands very rapidly, however, much faster than the speed of light, then you can create a lot of matter out of nothing by throwing negative energy past the Hubble sphere. This is the separator between space expanding slower than light and space expanding faster than light relative to your location. Ejecting negative energy causes the density of vacuum energy outside your Hubble sphere to reduce, and you get free matter and energy in exchange.

This reminds me of a brainstorm I once had called “negative cash.” Instead of waiting for your client to pay your bill, you just send them a negative check for the amount along with your invoice. No need to pay for your meal at the restaurant; the waiter simply hands you a stack of negative cash along with the check. Beware, though, of criminals who sneak up behind you and drop negative cash in your clothes; they‘re called “putpockets.”