by Jack H
Objects with mass warp the fabric of spacetime and create a gravitational field that attracts
other nearby objects. But how big is this field and how far out into space does it reach? We
understand that gravitational attraction gets weaker as your distance from the object
increases, but how far away would you have to go from an object to be completely out of its
gravitational reach? For example, it is easy to think that once you have left earth’s
atmosphere you become weightless and therefore you are no longer under the influence of
earth’s gravity. However, it is earth’s gravity that allows you to remain in orbit around our
planet, much like the International Space Station or the moon do. For a larger scale example
we can observe our solar system, the furthest thing that orbits our sun is ironically named
‘Farfarout’ and it orbits 132 times further out than we do. So this poses the question: how far
can a gravitational field reach? The unfortunately mind bending answer is that it reaches on
forever, an object on the other side of our universe will be influenced by our earth’s
gravitational field and we too will be influenced by its gravitational field. It will be an
incomprehensibly negligible force; however, it is still there. Therefore, there is no distance
you can travel to escape the gravitational pull of an object. On our planet, when you jump
there is an incredibly small astronomical distance between you and the earth beneath you
but because both you and the earth have mass, you are attracted to each other. This means
that you pull the earth towards you with an exponentially diminutive force, and this is over an
immensely short distance so imagine how negligible a gravitational force like this would be
over a large stretch of the universe.
Gravity is not what you think. The reason you are pulled towards large objects is the effect of
spacetime being warped. When you fall towards the earth, you aren’t moving, the earth is
rising to meet you. This would mean that the earth would have to expand outwards in all
directions to reach all falling objects at the same rate, and this would be a true statement.
However, the more massive an object in space, the more it warps spacetime. So as the
earth expands towards the falling objects, its size and mass increase and therefore the
space time it is situated in becomes more and more warped. These two phenomena (the
expansion of the earth and the shrinking of space time) are perfectly balanced, giving the
illusion that the earth remains the same size and yet there is still a constant force that pulls
everything towards it. This is what gravity truly is.
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