If gravity were to be gradually reduce by 7%, over the course or weeks of months, would an average human be likely to notice? Specifically the reduction in weight, not atmospheric changes or other consequences. Like one day, after the weeks of it changing, you roll out of bed and notice "hm, I feel lighter" or you notice that there is more bounce in your steps.

  • 1
    $\begingroup$ What human? A pilot, Formula 1 driver, office worker, physicist, postal worker, a jeweller or goldsmith? The people at weightwatchers might notice something but just put it down to coincidence - or not. $\endgroup$ Apr 29, 2020 at 20:46
  • $\begingroup$ If you fly from Oslo or Helsinki to Mexico City or Singapore you will experience a variation in gravitational acceleration of about 0.7% at the end of a few hours flight... And nobody notices a thing. $\endgroup$
    – AlexP
    Apr 29, 2020 at 20:49
  • $\begingroup$ The effect on atmospheric pressure might be a bit dramatic for 7%, also tea would taste odd because of the reduction in the boiling point of water. $\endgroup$ Apr 29, 2020 at 20:52
  • $\begingroup$ The boiling is something I wouldn't have noticed. I am not asking about environmental consequences, merely if an average human will notice the reduction in weight. $\endgroup$
    – NRJohnson
    Apr 29, 2020 at 20:55
  • $\begingroup$ Doctors would notice the spike in visits by folks with hypochondria and eating disorders. However, few of those folks are likely to feel lighter. They are merely pre-disposed to weigh themselves more often than normal. $\endgroup$
    – user535733
    Apr 29, 2020 at 20:56

2 Answers 2


It would be noticed way before you got to even 1%.

A lot of stuff humanity does depends on very high precision measurements of mass. Chemical and pharmaceutical industries would have their factory lines failing when you need to get X micrograms sample of something from a source weighting a ton and all of a sudden that sample has a density different than it was before.

Also notice that reducing Earth's gravity by any amount will cause all satellites to increase the mean radius of their orbits. A slight change in a single GPS satellite would cause its signal to be wrong and the satellite to be marked as unhealthy (thus being ignored by all devices). A slight change in all of GPS constellation at once? Nothing depending on GPS would work, and people would want answers ASAP!

  • 3
    $\begingroup$ The people of Earth rose up with one voice, demanding an answer to their shared question: "Where's the Doordash guy with my dinner?!" $\endgroup$ Apr 29, 2020 at 21:21
  • 1
    $\begingroup$ @AndrewBrēza my thoughts exactly :D $\endgroup$ Apr 29, 2020 at 21:22

Yes, if it happens quick enough. We rely strongly on our instinctive understanding of gravity and how it works. Everything about how we move including our gait is perfectly tuned to Earth's gravity. Every movement would feel wrong, people would notice that they couldn't throw objects properly anymore, and dropped items would fall noticeably slower. Pro and amateur athletes around the world would completely freak out and people who regularly lift heavy things for work (eg construction) can tell the difference when a bag of cement which is standardized to always weigh the same suddenly is easier to lift.


Not the answer you're looking for? Browse other questions tagged .