Summary
Highlights
Brian Cox introduces NASA's Space Power Facility in Ohio, the world's largest vacuum chamber, designed to test spacecraft in conditions mimicking outer space. It achieves this by pumping out 30 tons of air until only 2 grams remain. Built in the 1960s for nuclear propulsion system testing, its aluminum construction for radiation purposes necessitated a concrete skin to withstand external pressure when evacuated.
The video prepares to recreate Galileo's experiment: dropping a heavy and a light object simultaneously. Initially, with air present, a feather falls slower than a bowling ball due to air resistance. To observe the true nature of gravity, the air must be removed, requiring three hours to pump out 800,000 cubic feet of air to create a near-perfect vacuum.
After a three-hour process to create a near-perfect vacuum, the bowling ball and feather are simultaneously released. In the absence of air resistance, they fall at the exact same rate, hitting the ground together. This striking demonstration highlights that in a vacuum, mass does not affect the acceleration due to gravity.
The demonstration leads to a discussion of theories of gravity. Isaac Newton would explain the fall as a force (gravity) pulling them down. However, Albert Einstein famously imagined it differently, proposing that objects in freefall are not actually falling but are standing still, with no force acting on them. He reasoned that without observing the 'pull' of gravity, one couldn't tell if they were accelerating towards Earth, concluding they were not.