How were the pyramids built? Maybe with water
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For centuries, it's been a mystery as to how the ancient Egyptians moved the huge stone blocks needed to build the pyramids. Did they use sleds, ramps, wheels, logs? There's even a theory that aliens were involved.
Now researchers say they've found a much simpler technique to make the job easier: just add water.
How the builders transported stones weighing several tons from quarries all over the country has been an enduring mystery, according to the History Channel, AOL and The Washington Post.
If the researchers are right, the answer has been staring Egyptologists in the face for centuries. Check out the drawing of an Egyptian sled, above. What's that guy pouring?
It could just be plain old water. One of the most popular theories on how the Egyptians transported the stones is that they were hauled on sleds. Pulling a sled through sand is hard work. But it becomes much easier if the sand is wet.
Researchers carried out their own experiment and found if the sand is just wet enough, the sled can be pulled with half as much effort.
The study says that's because water gets between grains of sand and forms what they call "liquid bridges." They "act like glue, keeping the grains in place. This is great for sand castle building, and also, it turns out, for sand transportation," according to American Physical Society.
Basically, the water prevents the sled from digging into the sand and creating more friction.
Critical thinking challenge: Why did the ancient Egyptians use slaves instead of steam engines to move the blocks to build the pyramids?