If space is “empty”, then how come we can measure the temperature of the microwave background radiation?
Think about it…any direction we point an apparatus, we will get a reading — the static of a radio IS the CMB, and if you could take that radio into space, and have the ability to travel anywhere, that radio would still have static. As such, space cannot be “empty”, it’s filled with photons, electrons, and quarks, amongst other things.
To reach 0 Kelvin would take an infinite amount of energy (infinite is not exactly accurate but might as well be), hence “stupid expensive”. It would also create holes in the CMB. CMB has no holes, as such, there is stuff everywhere.
Think about it…any direction we point an apparatus, we will get a reading — the static of a radio IS the CMB, and if you could take that radio into space, and have the ability to travel anywhere, that radio would still have static. As such, space cannot be “empty”, it’s filled with photons, electrons, and quarks, amongst other things.
To reach 0 Kelvin would take an infinite amount of energy (infinite is not exactly accurate but might as well be), hence “stupid expensive”. It would also create holes in the CMB. CMB has no holes, as such, there is stuff everywhere.
Does that track?