Physicist: The original post is here.
The curvature of space alone has almost no effect on the movement of objects until they are moving really fast. With the exception of only the most extreme cases (black holes), space is very, very close to flat. For example, the total stretching of space due to the Earth amounts to less than 1cm. The precession of Mercury’s orbit is another example of the tiny effect of the curvature of space (and it is tiny). Literally, there’s a little more space near the Sun then there “should” be, and as a result the direction in which Mercury’s orbit is elliptical moves. It takes a little over 3 million years for it to go full circle.
In almost all cases the vast majority of an object’s movement is tied up in its forward movement through time. The curvature of spacetime (not just space) is responsible for gravity. Literally, near heavy objects, the “future direction” points slightly down. So anything that moves forward in time will find its trajectory pointing down slightly. This takes the form of downward acceleration. This acceleration (time pointing slightly down) is entirely responsible for the motion of the planets, and every other everyday experience of gravity.
In flat space traveling forward in time has no effect on your movement through space. In curved space (e.g., near a large blue mass) parallel lines can come together, and moving through time leads to movement downward.
It may seem a little confusing that, once you’re moving, the explanation doesn’t change and falling is still caused by movement through time. Well, there is some effect caused by spacial movement and the spacial part of the curvature, but these effects are almost completely overwhelmed by the effects from the time component of the velocity (much, much bigger).
This one was a really good definition.
Pleased to read you.
Cheers
Yoron.
I have been reading a lot about this topic and everybody seems to agree that time is curved. What I don’t understand then is why it doesn’t then become obvious that time MUST be circular. You cannot have a curve, no matter how miniscule, without it eventually becoming a circle. That is a fundamental rule of maths and physics. Therefore time is circular which therefore then becomes the simplest and tidiest explanation of the concept of infinity. Time must eventually come back upon itself and understanding life and the universe is really a matter of understanding how dimensions appear over repetitive circular time rather than linear time.
Peter Davy:
Graph x^2. You will see a curve that never forms a circle. Also, nothing else about what you said makes any sense. Luckily it doesn’t matter so have fun! : )
The Physicist: “In almost all cases the vast majority of an object’s movement is tied up in its forward movement through time.”
Exactly. Most visualizations don’t show the time dimension. The one below does:
Hi, im digressing slightly as im not sure where to post this question. The explanation of general relativity and the gravitational effects have often been compared to a bowling ball on a trampoline or a footbal on a blanket. Here is my question, if an object with vast density sits in space (like a bowling ball on a trampoline) thus bending spacetime toward it, does that mean if a particle passes this mass BENEATH it, it will NOT be attracted toward the mass?…….Furthermore, can space have an UPSIDE DOWN.
In order to be able to picture higher dimensional things, physicists frequently ignore one or two dimensions so that there are no more than three remaining dimensions (which is few enough to be pictured). In the bowling ball metaphor, the sheet is all of space. An object can’t pass above or beneath, because there is no above and beneath. For example, you can go anywhere on Earth, and move in any direction, and gravity will continue to work the same as always, because you’ll always be “on the sheet”.