Is the universe cooling down?

We find out if the cosmos is hotting up or cooling down

As the universe expands, it cools. Image Credit: NASA

As the universe expands, it cools. Image Credit: NASA

Asked by Kerry Stacey

Since the Big Bang the universe has been expanding and, as it expands, it’s cooling. We can measure the temperature of the universe by looking at the cosmic microwave background (CMB) – the thermal radiation left over from the Big Bang. By investigating the CMB scientists have been able to determine that its temperature has been dropping off smoothly as our universe pans out. The current average temperature of the cosmos is estimated to be around 2.73 Kelvin (-270 degrees Celsius/-455 degrees Fahrenheit).

The point of the Big Bang is described as an infinitely hot and dense singularity. The energy from the Big Bang spreads out as the universe expands, which gives us the cooling effect.

Asked by Zoe Baily from the National Space Centre

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