Products > Thermal Imaging

Thermal Imaging - Giza Pyramid

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bookaboo:
All over various news items are some "anomalies" found with the Giza pyramids.

http://www.bbc.co.uk/news/world-middle-east-34773856
http://www.dailymail.co.uk/sciencetech/article-3311075/Anomalies-thermal-scanning-Egypt-pyramids.html
http://www.express.co.uk/news/history/618350/Secret-passage-found-in-pyramid-Thermal-scans-show-STRANGE-heat-spots-and-hidden-chambers

All I can find so far are grainy photos of photos, I'd really love to have the images to import into Flir tools for evaluation (as well as the relevant data on ambient and reflected temperatures).

Reading very roughly off the scale (8°C span I think) it does appear that some stones are ~3°C hotter than their neighbours. But there also appears to be a ~2°C variation across the same stone, could be wind factors or thermal load of the "cooler" stone beside it but that strikes me as strange.... an indication that other factors may be at play, as such a large thermal mass as a lump of granite should not have significant temperature variations.

According to engineering tables granite has an emmissivity of 0.45, so reflections are a big issue, perhaps raising questions about the images. On the other hand this figure is much lower than I would have guessed intuitively, perhaps the tables are referring to machined granite. In any case, quite interesting.

CatalinaWOW:
Emissivity is supremely sensitive to the surface topography.  It is seldom dominated by the intrinsic properties of the material.  These apparent temperature differences could easily be the result of differences in surface weathering or dirt or differences in orientation of the tiny crystals of the various materials that make up granite.  Another answer would come from an instrument that uses two different spectral bands to estimate temperature, as emissivity is less likely to be wavelength dependent, or better yet, contact measurements with a thermocouple on particular areas which seem to show anomalies. 

bookaboo:
I was thinking that rough granite would have a high emmisivity, I wonder if the tables I found refer to polished granite like in kitchens etc. , that said there seems to be sky reflections on one of the photos. Although on reflection (pun intended) for the image anomaly to be caused by reflection the heat mass would need to be quite significant, using what looks like a person in the image for scale a reflected heat source would need to be several meters high. The only other reflection possibility I can think of would be the sun? In any case would be easy to verify with different angle images.

The other possibility would be the presence of moisture due to different material or surface. If my understanding is correct a damp stone would hold the heat longer at night.

If the idea of a hidden passage were correct would it show up like this? Assume they took an image in the morning as the sun warmed the cool stone, blocks with nothing behind them would in theory warm up faster as they have no thermal heat sink behind them.

CatalinaWOW:
While you can get thermal lags like this, it seems unlikely in this case.  If the hypothetical hidden passages were only a few centimeters from the surface they would definitely show such a signal under appropriate conditions.  But a rock wall that thin would have been obvious to any number of other observation techniques that have been used in the past.  If the passages are further from the surface the thermal signal will start to disappear for a couple of reasons.  First the thermal time constant gets long relative to a day.  Secondly, the passages need to be human scale, or else cave-ins or detections be other means would have occurred.  But if human scale, lateral heat spreading tends to blur any signal.

That leaves you with theories only the ancient astronaut or crystal energy crowds could believe.  Theories like "The materials of these rocks were engineered to have different thermal characteristics so that they could be detected once a sufficiently advanced civilization developed."  And they predicted how far in the future that would occur so that the engineered rocks would be on the surface after the theft of the surfacing stones and erosion/weathering of the layers underneath.

As an aside, I thought the pyramids were mostly constructed of limestone with granite only on a few interior walls and features.  Same arguments about emissivity apply to limestone.  If granite is seen on currently exposed faces of the pyramids that is a far bigger clue to interior passages than any thermal differences.

bookaboo:
Indeed you are right, limestone was used on the outside granite only on the chambers.


The image in question:



I wonder if water could have accumulated somehow increasing the thermal capacity.




But I wonder what they are doing here, surely inside a pyramid chamber will be as close to equilibrium as you can possibly get, even if there was air behind a stone it's not going to have enough heat mass to change the surface temperature, unless as you say its a very thin stone sheet.




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