Final answer:
The theory of gravity explains that two water bulges form on Earth due to the Moon's gravitational pull, leading to the tidal movements we observe. These bulges result from water flowing and accumulating on the sides of Earth aligned with the Moon's position, not from water being lifted or compressed away from Earth. Earth's rotation causes the tidal cycle of two high and two low tides daily.
Step-by-step explanation:
The theory of gravity explains the formation of tides as a result of the gravitational pull of the Moon on the Earth's oceans. There are two water bulges because the side of Earth closest to the Moon experiences a stronger gravitational pull, resulting in the water being drawn towards the Moon, creating a bulge.
The opposite occurs on the far side of Earth due to the gravitational forces pulling the Earth itself more than the water, leading to another bulge on the opposite side, just like an American football shape elongated towards the Moon. As the Earth rotates, these bulges move around with the planet, causing the tidal movements and water accumulation we observe as high and low tides.
What is often misunderstood is that these tidal bulges do not result from the Moon compressing or expanding the water, nor from lifting it away from Earth, but rather from a flow of water over the Earth's surface, which accumulates at regions below and opposite the Moon due to differential forces.
The Earth rotates underneath these bulges resulting in two high tides and two low tides each day. Moreover, the slight displacement of these bulges also impacts the Moon, pulling it ahead in its orbit. The tide-raising forces are generally too small to affect solid objects but have a significant effect on the movement of oceans.