# Active Reading Solution: The Higgs/Water Analogy

• Perhaps the biggest limitation of the analogy is that water tends to reduce an object's velocity; the Higgs field (or mass) reduces acceleration. Those two effects look very similar when you're trying to speed something up. Push on a still block under water, and the water makes it harder to get the block moving. Push on a very massive object in outer space, and its high mass makes it harder to get the object moving. That's why the analogy works at all.

But if a block is already moving through water, the water tends to slow it down. If a massive object is already moving through space, its large mass makes it harder to slow. So now the analogy works backward!

Of course, the whole distinction between "speeding up an object" and "slowing down an object" in outer space is reference frame dependent. Water picks out one particular reference frame, and slows everything down relative to that frame. The Higgs field does not establish a preferred reference frame.

• Another limitation of the analogy is that mass—and therefore the Higgs field—actually has two very different effects. One effect is inertia (a larger object is harder to accelerate, as discussed above). The second effect is gravity: a larger object creates, and experiences, a greater gravitational force. This second effect is not reflected in the water analogy.

• Finally, note that water does not create an object's inertia; it only increases it. Move the object into the air and it becomes easier to move; put it in outer space, and it is still easier. But no matter where you put it, the object still has some mass, and responds to a force with a finite acceleration. Without the Higgs field, all objects would be literally massless!