private void physicsInvaders() {
		Invader invader;
		invader = invaders[0][0];
		if (invader.getX() < 5) {
			invaderSpeedX = invaderSpeedX * -1;
			invaderLimit = true;
		}
		invader = invaders[COLUMNS - 1][ROWS - 1];
		if (invader.getX() + invader.getTexture().getW() > Window.getW() - 5) {
			invaderSpeedX = invaderSpeedX * -1;
			invaderLimit = true;
		}

		for (int column = 0; column < COLUMNS; column++) {
			for (int row = 0; row < ROWS; row++) {
				invader = invaders[column][row];
				invader.setX(invader.getX() + invaderSpeedX * App.getFTime());
				if (invaderLimit) {
					if (invader.getY() > Window.getH())
						invadersNumber = 0; // Eliminar
					invader.setY(invader.getY() + invaderSpeedY
							* App.getFTime());
				}
			}
		}
		invaderLimit = false;
		if (invadersNumber == 0) {
			startInvaders();
		}
	}