摘要
依據牛頓的萬有引力定律：重力與距離的平方成反比，也就是說：重力是無遠弗屆的。在本次演示中我們將體驗：重力的確在地球表面消失了。在愛因斯坦的最後一個生日（1955年3月14日）他的鄰居Eric Rogers送給他一個玩具，該玩具以一個彈簧固定在窗簾用的銅棒內，彈簧很軟，一條繩子繫著彈簧一端，另一端穿過固定在銅棒端的金屬碗中央的小孔，使重球倒掛在碗外；玩法是：運動銅棒，要讓重球落入金屬碗內。聽聽愛因斯坦的敘述與作法：「我現在讓它落下，根據等效原理，球應該不受重力，這時彈簧的強度就足以將球拉至碗內。」他將銅棒舉起，金屬碗接近天花板，將棒自由落下，並維持棒與地面的垂直，當棒一端接近地面時，以手接住，而球已在金屬碗內。（軟弱的的彈簧趁著銅棒向下加速，重力場被加速度抵銷的瞬間、表現了一下）。我以鋁桿代替銅棒，滑鼠球代替重球，彈簧為品質好的電話線的捲曲部分，製成該玩具，作為教具，該玩具對演示等效原理，除了具有重複演示的功能；對於示範者或體驗者亦具挑戰性（球是否落入金屬碗內），著實為一有趣之演示教具；此外，前人的智慧，並與愛因斯坦貼近的歷史意義等優點，使其成為一極佳的演示教具。
並列摘要
At the Einstein's last birthday (14th march 1955), Einstein's friend Eric Rogers gave him a toy as a gift. This toy was made from an idea of principle of equivalence.The toy was composed of four parts, a soft spring, an iron ball, a bowl, and a tube. The spring was fixed inside the tube. On the other end of the spring, there was a line through the bottom of the bowl, then connected with an iron ball. The ball outside the bowl was pull by two forces, one from the gravity of the earth was downward, the other one from the spring was upward. The spring was soft, and it could not pull the ball into the bowl. When Einstein had the toy free fall to the ground, the ball was pull into the bowl by the soft spring. Because of principle of equivalence, acceleration downward was equivalent to gravitational force, the gravity disappeared.I also make a toy such as Einstein ever had one 54 years ago. As a teaching work used in an activity about the principle of equivalence, it can be played repeatedly compared with other similar ones such as the free falling elevator and the free falling fire of candle. Also it is interesting and a challenge for the player to know how dose the ball can be pull into the bowl. From the vision of history, it is a meaningful activity that we can evenly such close to the Einstein’s age and Einstein himself. At last, it is admirable that Mr. Roger could invent this toy just depending on the understanding of general relativity.