In the 16th and 17th centuries, the motion of the Earth was a hot topic of debate. X considered his theory of the tides to provide the required physical proof of the motion of the earth. For X, the tides were caused by the sloshing back and forth of water in the seas as a point on the Earth's surface sped up and slowed down because of the Earth's rotation on its axis and revolution around the Sun.
If this theory were correct, there would be only one high tide per day. X and his contemporaries were aware of this inadequacy because there are two daily high tides at Venice instead of one, about twelve hours apart. X dismissed this anomaly as the result of several secondary causes, including the shape of the sea, its depth, and other factors.
X dismissed as a "useless fiction" the idea, held by his contemporary Y, that the moon caused the tides. X also refused to accept Y's elliptical orbits of the planets, considering the circle the "perfect" shape for planetary orbits.
Against the assertion that X was deceptive in making these arguments, Albert Einstein expressed the opinion that X developed his "fascinating arguments" and accepted them uncritically out of a desire for physical proof of the motion of the Earth.
Identify the famous and highly respected scientists X and Y.
Hint: There is a famous conjecture about sphere packing, named after Y.