5 ms·

It's difficult because it is completely unintuitive, and I'm not sure we can ever experience it - or even conceive of experiencing it. It helped me to wrap my

by soneil 11y ago

It's difficult because it is completely unintuitive, and I'm not sure we can ever experience it - or even conceive of experiencing it. It helped me to wrap my head around it by comparing it to gravity. If you pick up 1kg of material and place it on a scale, it'll weigh 1kg. If you take that same scale to the moon, and place 1kg of material on it, it'll weigh 1kg. And we can objectively experience that - if we pick up that 1kg on the moon, it'll feel like a bag of sugar. And this should be the same for time. The clock taken to relativistic speeds will still measure 1 minute as 1 minute. The difference is that in the case of gravity, we can measure that same mass from a distance - we can bring it home and experience it again relative to a different gravity. It's much less intuitive to measure time from a distance.

powertower 11y ago
A kg is a measure of mass, not weight. Weight requires 2 general objects, and is dependent on gravity (between them). Mass does not. 1kg of material in outer-space will weight zero. And on the moon, about 1/6 of what it weights on earth. While its mass will remain the same. Your scale would have to be re-calibrated for the change in gravity to produce the same reading between the measure on earth and the moon - for both weight and mass of an object (a scale can only measure weight, which then has to be converted to mass using the already predetermined gravity force at the location)... Unless it was a really fancy one with some mechanism that could also measure gravity.
- soneil 11y ago
  I'm using an uncalibrated scale intentionally, as that's exactly what we're doing when we talk about taking two clocks and moving one of them at relativistic speeds. That two identical instruments in different gravitational fields will exhibit different measurements. With mass this makes sense to us, because we can compare with a constant - we can take the same item with a constant mass and measure it in two different gravities - and because it happens on scales we can perceive. Men bouncing around the moon is a perceivable change. An astronaut coming back from a year on the ISS, being biologically 12.5 seconds younger than if he hadn't gone, is far too glacial for humans to perceive. Of course, we could just argue that relativity is a myth and the clocks just need to be calibrated.

by soneil 11y ago

powertower 11y ago

A kg is a measure of mass, not weight. Weight requires 2 general objects, and is dependent on gravity (between them). Mass does not. 1kg of material in outer-space will weight zero. And on the moon, about 1/6 of what it weights on earth. While its mass will remain the same. Your scale would have to be re-calibrated for the change in gravity to produce the same reading between the measure on earth and the moon - for both weight and mass of an object (a scale can only measure weight, which then has to be converted to mass using the already predetermined gravity force at the location)... Unless it was a really fancy one with some mechanism that could also measure gravity.

soneil 11y ago
I'm using an uncalibrated scale intentionally, as that's exactly what we're doing when we talk about taking two clocks and moving one of them at relativistic speeds. That two identical instruments in different gravitational fields will exhibit different measurements. With mass this makes sense to us, because we can compare with a constant - we can take the same item with a constant mass and measure it in two different gravities - and because it happens on scales we can perceive. Men bouncing around the moon is a perceivable change. An astronaut coming back from a year on the ISS, being biologically 12.5 seconds younger than if he hadn't gone, is far too glacial for humans to perceive. Of course, we could just argue that relativity is a myth and the clocks just need to be calibrated.