Assuming that it's impossible to circumvent the laws of physics, is it possible to defy them?
That is, in order to defy something, do you necessarily have to have some success in resisting it, or can your defiance be totally futile?
First, let's take a look at the definition of defy:
In most cases, the idiom defying the laws of physics appears to be using the second sense of the word. Consider these examples:
In this case, it appears that the phrase is to describe something which defies the conventional notion of physical reality. If it truly were possible to build such a spaceship, it wouldn't violating the fundamental nature of the universe, but it would change our understanding of it.
In this case, it's a bit of hyperbole. It's well understood that the gymnast is not doing something truly physically impossible—unless she's levitating—but is merely presenting a performance that is so physically demanding, the speaker was amazed.
There are also contexts where it might be using the third sense of the word, for example:
Here, the speaker is means that his model presents a substantial challenge to the currently accepted laws of physics. In the future the new model might be accepted in favor of the current laws. Of course, the model is just an idea with no physical form, so it cannot do any defying by itself.
Here, the action scenes are described pejoratively as too unrealistic to be believable. The director is simply disregarding the laws of physics for the purpose of entertainment.
I could defy or challenge the laws of physics to operate in a particular circumstance, such as by jumping off a tall building and expecting to float to the ground without getting hurt. In such a challenge or act of defiance, I would lose to those laws. One may certainly defy civil laws and in some cases you will get away with doing so, but defying the laws of physics in the wrong way can get you in real trouble. Still, you may defy them if you want. As a physicist you would expect that subjecting material to pressure would result in a material with a higher density if only when under that pressure. In fact in the case of the experiment that started this discussion, stating that the result "defied the laws of physics" is shorthand for the fact that the material that resulted was less dense than what they started with. Of course, the material became porous and if you measured the true density of the material with the pores emptied of the fluid, the density may or may not have been lower, but the factor of two difference would surely not have obtained. Different physical "phases" or rearrangement of the molecules often results in variations in density but in this case the material had known porosity-that, in fact, was the main benefit that may give the material practical value.