If there's nothing in empty space, then how does it get warped by gravity?

[Arkilogue]

And who's to say space is warped ?

Thought experiment:

you're blazing through space in your little excursion pod at 1% the speed of light.  "Oh look !!"  you exclaim "I'm going to pass near a star, I bet this will be fun!!"

So there you go at 1% the speed of light, passing very close to a star.  You're going fast enough the heat and light and radiation will not hurt you or your excursion pod.  The star is coming up fast on your right, and zoom!  You go past it and off into the inky depths.  

And then you think for a second, "Hmm, odd, I never touched the steering controls, and I never felt any sideways force at all, but I'm traveling in a slightly different direction now!  What happened?"

Indeed, you're confused, you peer straight ahead through the view screen, and the direction you are traveling is now slightly different, you're aimed a bit off that 3rd star to the right you aimed at months ago.  But you never felt a thing, and your excursion pod never thrusted to change your direction at all.

So, did you turn, because it sure looks like you did, or did you travel in a straight line, because that is exactly what it feels like and you never fired thrusters to change direction?

The mass of the star attracted you and your passing vessel whether you were able to perceive it or not.

But I'm wondering how do particles "know" there are other particle out there in space and why do they aggregate?