the huge stone blocks needed to build the pyramids: sleds, ramps, wheels, logs ... aliens.

Now, Dutch researchers say they've found a much simpler technique to make the job easier:

just add water.

Yep, how the builders transported stones weighing several tons from quarries all over the country

has been an enduring mystery.

"There is still a great deal of disagreement among Egyptologists about how the pyramids

were actually constructed." (Via History Channel)

But if the researchers are right, the answer has been staring those Egyptologists in the

face for centuries. Check out this guy on the front of the sled. What's he pouring?

(Via Wikimedia Commons / Sir John Gardner Wilkinson)

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.

In the study, published in Physical Review Letters, the Dutch 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" which "act like glue, keeping the grains in place. This is great for sand castle

building, and also, it turns out, for sand transportation." (Via American Physical Society)

Basically, the water prevents the sled from digging into the sand and creating more friction.

It's not exactly rocket science.

It's also not a new idea. This BBC documentary has its actors pouring water in front of the

sled. But now we know how that made the job easier, and we're sure the guys holding the

ropes appreciated the help.