If the CMB is in all of space, how does the Earth not get cooked in it?
In: 255
Cosmic microwave background is the name of the waves hitting us all the time from all directions. It is like the temperature of the universe. Although it has the word microwave in it it has little to do with a microwave oven. A microwave is the name of a band of the electromagnetic spectrum. A microwave oven makes microwaves of a certain frequency that can make water molecules spin. The oven makes high amplitude waves that make water molecules spin fast. As they spin they hit the surrounding molecules and everything gets moving faster and heats up.
The CMB is more like the glow of something hot. Think of something very hot that glows white. As it cools it glows red and eventually it glows in a way we can’t see but you can put your hand near it and it still is radiating heat. This is infrared radiation. As it keeps cooling the waves it emits get longer and longer.
The universe started out hot and is cooling. It has cooled so much that it’s radiating in the microwave region. The temperature of this radiation is 2-3 degrees K. If we somehow cooled an object to close to absolute zero and left it in our in space somewhere, away from any stars. It would warm to that temperature because of the CMB. Since most things on earth are hotter than that temperature we are radiating out into the CMB but not gaining any energy from it.
Latest Answers