你有沒有玩過吹肥皂泡的游戲？用吸管沾著肥皂水，吹出一長串的泡泡。這些泡泡在空中漂浮，撞在一起的時候常常會粘在一起，形成一大團泡泡。你知道泡泡為什么會粘在一起嗎？下面這篇短文就來告訴您這個秘密。

Surface tension!

Surface tension plays matchmaker in changing the status of a bubble from being single and solitary, to being part of a couple, or part of a multiple bubble group.

Uniting the bubbles temporarily destroys the surface tension's equilibrium, but once the surface tension joins the bubbles, it establishes a new balance.

The internal air pressure of the single, solitary bubble slightly exceeds that of the air surrounding it, because the surface tension reduces the bubble's surface as it squeezes it into its round shape. The product of being squeezed is a buoyant bubble, which rises to the top of the water's surface, because of its own inner water level. The bubble happily floats about, surrounded by uniform surface tension, guided by the momentum it picked up when being formed, and by changes in air pressure.

In turbulent water, the surface tension pulls the water's surface into a slope, or meniscus, the bubble rides the wave, and floats to its crest.

The meniscus, though it does not extend far into the water, manages to divert the bubbles' attention away from each other to objects, such as the sides of the bathtub, a human body, a rubber ducky, etc. Because the slope's extension range is short, the range of the force between the bubbles is also short.

Two or more bubbles drifting close to each other do not pass each other like ships in the night if their surface tensions overlap. This overlap destroys their equilibrium, and, to compensate for the low tension between the bubbles, the high surface tension surrounding them forces them together and restores their equilibrium. If, however, the surface tension forces them together too rapidly, we have a case of fatal attraction, as the two bubbles collide and burst.

Technically speaking, when the bubbles meet, they join at the point of the smallest surface area and, if they join in the middle of calm waters, the energy level they give off as they connect can be seen to the naked eye as circular ripples. Alone together at last.

（來源：coolquiz.com 英語點津 Annabel 編輯）