I thought we still weren&#x27;t quite sure why bicycles don&#x27;t topple over or why ice skating is possible:<p><a href="http:&#x2F;&#x2F;www.nytimes.com&#x2F;2006&#x2F;02&#x2F;21&#x2F;science&#x2F;21ice.html" rel="nofollow">http:&#x2F;&#x2F;www.nytimes.com&#x2F;2006&#x2F;02&#x2F;21&#x2F;science&#x2F;21ice.html</a><p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Bicycle_and_motorcycle_dynamics#Other_hypotheses" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Bicycle_and_motorcycle_dynamic...</a><p>Also, have we figured out gravity? That&#x27;s a pretty every day thing that I thought we didn&#x27;t understand yet. Has observing gravity waves given us an answer there?