Is there such a thing as an absolute maximum temperature?
I asked myself that exact same question. But the answer is a little silly and perhaps not surprising. You see, what you must understand is that a massive (i.e. with mass) object cannot reach the speed of light, because it can be shown with a relatively simple proof that the amount of energy needed to accelerate it to the speed of light is infinite. Here lies the answer to your question: to accelerate something with mass (like matter) to the speed of light (the speed limit) you need infinite energy, or, in other words, an infinite quantity of heat. This obviously means, that you can go on increasing the temperature of an object forever and it won’t ever reach the speed of light. Therefore, there is not “upper-limit” to temperature.
