Neil DeGrasse Tyson invites you to a podcast panel and asks this:

Neil Degrasse Tyson invites you to a podcast panel with two other physicists and presents this for you to explain or refute away:

"Gravity can be thought of as mass falling back to where the big bang originated."

A description follows to lead you into the podcast:

Gravity in part describes things being attracted to their local center of mass. If you drop an apple on earth, it falls toward the center of the earth. Drop an apple on the moon, it falls to the center of the moon.

Our 3d 'space' is often described by bringing things down a dimension conceptually - we describe existing as a 2D shape on a 2D balloon surface. This balloon is expanding in 3d, and as it does those shapes on the surface move away from each other.

There is no central point on this balloon surface that's the 'center' of this expansion, the center of the expansion is fully outside of the 2D balloon surface.

But it exists, and a vector can be drawn that points at that center, like a line segment can be dropped below the balloon's surface to meet the topological center of that balloon. Conceptually this can be described as the point where the balloon is expanding 'from', but it fully exists outside of the structure of the balloon surface - it has to, if it exists at all.

So far, a fairly accepted topology model, a way of 'looking at it' that doesn't for our purposes require experimentation to hold conceptually in our minds.

Now imagine a bowling ball resting still on a trampoline, and note the deformation of that trampoline.

If you drop that bowling ball on that trampoline, it deforms it more. But if you keep the bowling ball resting stationary and raise the trampoline at the exact same speed/acceleration, it will deform the trampoline surface *exactly* as much as if you dropped the ball onto it - in fact, this inertial frame of reference is identical to dropping the ball on it - there is no difference, physically.

Now think of the shapes on that expanding balloon surface having mass and deforming the surface of the balloon as it expands 3 dimensionally. We can describe how these masses will move toward each other as the balloon surface deforms - just as that trampoline deforms when moving at the same speed as the 'falling' ball, it's how suns, planets, black holes form.

Drawing a vector from any area of mass on that balloon surface to where something 'falls to' will point at it's local center of gravity contained in it's now-deformed 2D brane, and the center of the 3D brane (balloon) ---> at the same time.

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Now, Neil's question to you and the other two physicists on the panel:

How is this *wrong*, how specifically does it refute, let's say, what our favorite current topological model says?

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