Coming to a sudden stop and changing directions is not beyond known physics. Like I said, all you need is a large thrust or a light object or some combination of the two.
Really? Okay, prove it.
Show me your "known physics" which you seem to be so confident of knowing:
A) How light would this 40 foot object need to be?
B) How much thrust would it need to achieve this?
C) What's the max G-Force load it would experience?
D) How strong would this material need to be to absorb C
E) Now add the heat requirement for hypersonic velocities (which was also observed.)
F) What's the lightest material that can satisfy D and E?
Once you have a preliminary number for F, then plug it back into A, and we'll see your final result for B, C, D & E.
Good luck.
Commander Fravor made a visual observation from a significant distance away, how would he be able to tell if the direction change was truly instantaneous or not?
There are 3 problems with this:
1) The first possibility Fravor considered was that it was a helicopter (which is equivalent to your hypothesis because it would still require vertical thrust to maintain altitude). He ruled it out because there was no rotor wash on the surface of the water (this effect would exist for any type of conventional thrust generated at that altitude.)
2) Fravor and his flight are subject matter experts. They're fighter pilots. Fravor is also a graduate of Top Gun. So if he's claiming that visibility + contrast + range to bogey was not an issue for his observation, he's probably right.
3) You also need the radar equipment to be malfunctioning during this 'tic tac' episode. Plus, you need the recent footage taken by the destroyer to be faked, in order to explain all of this.
Now, given all of the above, you should have said that this whole thing is just a hoax, and everyone involved is simply lying and providing doctored evidence. That's at least a much simpler explanation. However, personally, at this point, I'm leaning towards the other possibility, that these things actually do exist, and they are not human technology. And again, I'm only saying this after listening to Fravor's account. I personally could not detect any BS in his testimony. And if this is an organized lie by the Pentagon, Fravor would necessarily need to be lying.