Is the temperature in the vacuum of space -273.15 degrees celcius

At absolute zero all levels of matter that we are able to measure stop moving. Anything colder is presently irrelevant because we would have no means to measure it by at present.

Could have sworn they could make objects less than 0 Kelvin by making it negative and giving it weird properties a result 🤔 can't really remember

-273.15 is the lowest temperature possible. At that temperature any atom of any kind stops moving. SO that's the final lowest temperature.