New research by physicists at the University of California, Berkley suggests that in order for the laws of physics to hold, the universe can not be finite in space or time. This means that time would have to stop at some point and they’ve calculated that this point has a 50% likelihood of occurrence within the next 3.7 billion years.
Look out into space and the signs are plain to see. The universe began in a Big Bang event some 13 billion years ago and has been expanding ever since. And the best evidence from the distance reaches of the cosmos is that this expansion is accelerating.
That has an important but unavoidable consequence: it means the universe will expand forever. And a universe that expands forever is infinite and eternal.
Today, a group of physicists rebel against this idea. They say an infinitely expanding universe cannot be so because the laws of physics do not work in an infinite cosmos. For these laws to make any sense, the universe must end, say Raphael Bousso at the University of California, Berkeley and few pals. And they have calculated when that is most likely to happen.
Their argument is deceptively simple and surprisingly powerful. Here’s how it goes. If the universe lasts forever, then any event that can happen, will happen, no matter how unlikely. In fact, this event will happen an infinite number of times.
This leads to a problem. When there are an infinite number of instances of every possible observation, it becomes impossible to determine the probabilities of any of these events occurring. And when that happens, the laws of physics simply don’t apply. They just break down. “This is known as the “measure problem” of eternal inflation,” say Bousso and buddies.
Of course, their model makes an important assumption about the laws of physics. They assume that we should be able to understand why they work instead of just being able to observe that they do work.
Time Likely to End Within Earth’s Lifespan, Say Physicists [MIT Tech Review]