Immediately after the Big Bang, the temperature was unimaginably high, likely in the trillions of degrees Kelvin. This is so hot that it's difficult to even comprehend.
To give you an idea:
* The surface of the sun is about 5,500 degrees Celsius (9,932 degrees Fahrenheit).
* The hottest man-made temperature ever reached was about 4 trillion degrees Celsius (7.2 trillion degrees Fahrenheit) in a particle accelerator.
The temperature of the universe cooled rapidly as it expanded, but even after billions of years, the remnants of that initial heat are still detectable in the form of the cosmic microwave background radiation.
While we can't precisely state the exact temperature at the absolute beginning, the Big Bang theory suggests it was incredibly high, far exceeding anything we can experience today.
