There have been more recent studies which strongly suggest that the granite blocks in the Great Pyramid were cut and shaped 30 to 35 thousand years ago. This is a radiological dating utilizing the differential rate of radioactive decay of the radioactive materials naturally occurring inside of All Granite. When radioactive material is fully surrounded by other radioactive material, it decays at a particular rate. When that same radioactive material has "open air" on one side and "solid granite" on the other side, it will decay at a different rate. Based upon this differential decay rate, (I forget who) dated the granite used in the Great Pyramid to 30-35 thousand years ago. The Egyptians that we know of did not exist >15 thousand years ago, let alone >30 thousand years ago.
It should also be noted that none of the pyramids in Egypt have hieroglyphics inside of them. This is extremely unusual as ALL known Egyptian architecture is covered from ceiling to floor in hieroglyphics. As the pyramids are the only "Egyptian" structures which totally lack hieroglyphics, it is logical to assume that the Egyptians had nothing to do with their construction.
Egyptologists have Never found a mummy or any burial related item inside any pyramid. All of the burial related items (and mummies) were buried in separate structures (the burial temples) constructed at or near the base of the pyramids. These burial temples are covered from ceiling to floor in hieroglyphics and show significantly different architecture than the core stone construction of the pyramids. There is no reason to believe that the pyramids have anything to do with the "relatively new" burial temples even if those burial temples were constructed next to the pyramids purposefully (as their is plenty of evidence that the Egyptians had great reverence for the pyramids).
It should also be noted that the Egyptian records talk about "restoring" the pyramids and they never talk about "building" the pyramids. The Egyptians are extremely precise on this point.
As for the Sphinx, recent geologic dating suggests that the Sphinx was constructed prior to the desertification of the Egyptian region, which completed the climate change more than 7 thousand years ago. (About 12 thousand to about 7 thousand years ago, there was less and less rain on the Giza plateau with the present "lack of rain" being mostly unchanged from about 7 thousand years ago to present). The measurements of the water damage to the cut stones surrounding the Sphinx (and the Sphinx temple which was made out of some of those stones) suggest that the Sphinx (and it's temple) are greater than 12 thousand years old. Again, it is unlikely that the Egyptians that we know of could have had something to do with it.
I agree that the pyramids are neither power-plants nor extraterrestrial, but they are not "new" either (they are probably thousands if not tens of thousands of years older than Egyptologists are willing to admit).
As for another strange thing about All of the pyramids, they all show internal signs of water damage, as if they were underwater for weeks. Approximately 12 thousand years ago a (comet or asteroid) impacted the Indian Ocean (somewhere north-east of Madagascar), and impact modeling suggests that Egypt would have been underwater for about 40 days or so as a result of the tidal wave from this impact (not to mention the noteworthy flooding which would have occurred hundreds of miles into the lands along the shore line from ~India to the southern tip of South Africa). This piece of evidence seems to suggest that even the "youngest" "Egyptian" pyramid is still greater than 12 thousand years old.
One further interesting "coincidence" on this flooding point is that every pyramid on the Giza plateau has a "drain" in the lowest chamber which connects to the "sponge-like" rock layer under the Giza plateau - as of such, the upper chambers in these pyramids would have remained dry even as the pyramid remained underwater for weeks as the water leaking in would have drained out at the required rate. It can be hypothesized that a few people could have stored a few weeks worth of food and drink in the upper chambers of each pyramid during this impact and flooding event so as to survive while the water levels subsided.
I would also like to note that the mastabas and stacked mastabas are not pyramids and none of them show internal water damage. (most of them contain hieroglyphic scripting too).
The Pyramids of Egypt have many mysteries.
It is too soon to write them off.