In general relativity, a geodesic generalizes the notion of a "straight line" to curved spacetime. Importantly, the world line of a particle free from all external, non-gravitational forces is a particular type of geodesic. In other words, a freely moving or falling particle always moves along a geodesic.
Is gravity a geodesic?
The concept of "gravity" is then that objects are falling along the bending of spacetime. The path that objects follow is called a "geodesic".
What causes spacetime to warp?
Large objects such as the Sun and planets aren't the only masses that warp the fabric of space-time. Anything with mass—including your body—bends this four-dimensional cosmic grid. The warp, in turn, creates the effect of gravity, redirecting the path of objects that travel into it.
Is an orbit a geodesic?
Whatever the origin of the velocity: every orbit is a geodesic. The criterium is that the object in motion isn't pulling G's. For any object the shape of the geodesic that it is moving along follows from both the distribution of gravity and the velocity of the object with respect to that distribution of gravity.
Do all objects follow geodesics?
It is this curvature of spacetime that gives rise to what we interpret as gravitational acceleration. Note that there is no mass in this equation – it doesn't matter what the mass of the object is, they all follow the same geodesic (so long as it's not massless, in which case things are a little different).
Are geodesics straight?
A geodesic is a locally length-minimizing curve. Equivalently, it is a path that a particle which is not accelerating would follow. In the plane, the geodesics are straight lines.
What did Einstein say about time being an illusion?
Albert Einstein once wrote: People like us who believe in physics know that the distinction between past, present and future is only a stubbornly persistent illusion. Time, in other words, he said, is an illusion. Many physicists since have shared this view, that true reality is timeless.
What did Einstein mean when he said that gravity warps space?
Gravity is the curvature of spacetime It is here that Einstein connected the dots to suggest that gravity is the warping of space and time. Gravity is the curvature of the universe, caused by massive bodies, which determines the path that objects travel. That curvature is dynamical, moving as those objects move.
Does Earth warp spacetime?
Gravity, Einstein asserted, is caused by a warping of space and time—or, in a language we physicists prefer, by a warping of spacetime. The Earth's matter produces the warpage, and that warpage in turn is manifest by gravity's inward tug, toward the Earth's center.
Why gravity is not a force?
In general relativity, gravity is not a force between masses. Instead gravity is an effect of the warping of space and time in the presence of mass. Without a force acting upon it, an object will move in a straight line.