New research suggests that dark energy isn't needed to explain the acceleration in the expansion of the universe — instead suggesting giant voids in space are creating an illusion. When you ...

They found that their model's prediction matched what the Parker Solar Probe reported: particle acceleration and escape across a range of energy levels. The probe was very close to the sun—for ...

As we saw in our last lecture, the velocity of a point is always tangent to the path of that point. The acceleration of a point will always have a normal component that points inward on the path. Can ...