Has anyone here ever asked these questions about the balloon analogy? 1. If the universe actually was the 3D surface volume of an expanding 4D hypersphere, how big would the radius be? (let the radius of the observable universe be 46.25 billion light years) 2. How fast is it expanding? (let the age be 13.8 billion years , via Planck mission) 3. What is the fractional change in the circumference of this hypothetical 4D hypersphere? That is, divide the change in the entire circumference by the circumference. The answers are eye-catching.