Thermal Imagers


Thermal imagers seem to be one of the most sought after tools for paranormal research. In my opinion it is because they are expensive, and the fact that they appear on TV shows just adds to the Pied Piper Para-Zombie frenzy.

So why do paranormal researchers want these tools and what do they think they will see if they get one? The most obvious reason is that they think that ghosts will show up in thermal imagers when they are not visible in normal light. So cold figures are most likely what they would be seeking. Some researchers hypothesize that ghosts or spirits can manipulate energy to manifest and that these anomalies will show up in thermal imagers; this is a very popular belief in the paranormal community.

Thermal imaging works by detecting and measuring the infrared radiation emitted by an object, person or animal. Anything above zero degrees Kelvin, also known as absolute zero, emits some measureable amount of infrared energy. According to IR Camera Experts, to get a reading of temperature using thermal imaging, the camera runs a series of algorithms based upon the infrared radiation emitted by an object and its emissivity. No object radiates all of its temperature as infrared radiation; thermal imaging cameras use emissivity, the percentage of the thermal radiation emitted to the true temperature of the object to provide a more accurate read of the object’s temperature. Using these algorithms, the thermal cameras can create an image of the environment without the need for visible light with accurate temperature readings.

So based on current hypotheses, is it possible to see a cold mass moving through the environment?  Not really, A cold area can be a real area of lower temperature or one that feels colder. Even if a cold spot really is physically colder, a thermal camera couldn’t see it.  Like IR laser thermometers, it picks up temperatures from object surfaces not the air. So a cold pocket of air will not show up in a thermal imager. On the other hand, an imager might reveal a cold surface that is a direct result of being exposed to cold air, like a window sill.

What about spirits? The idea that spirits should show up in thermal imagers isn’t likely,  there is nothing that would support that it is even possible based on what we hypothesize a ghost or spirit to be. So called figures and other anomalies have appeared in thermal cameras but there could be other reasons for this. This doesn’t mean ghosts can’t appear in thermal imagers, just that there is no evidence yet that they do, since we still have no idea what ghosts consist of. But if it does manifest as a cold spot, a thermal imager won’t be able to see it.

How does a thermal imager work? Before you go and drop a few thousand dollars, I suggest you understand how one really works.. Many people think they are getting a ‘heat viewer’ but it is not quite as simple as that. Look at it like this, despite its name, it is like a camera. However, instead of recording visible light, it shows mid- and far-infrared radiation. Most surfaces in direct line of sight to the thermal imager will give a temperature reading. That’s because they emit mid-far-IR, rather than reflect it. Since the image shows the temperature, rather than light reflected, there can be hot and cold spots that wouldn’t appear in a normal photograph. Also, a surface may appear warm or cool after having been in contact with a hot or cold object.

For instance, a chair may show a warm image of a human for a while after they get up. Unlike light, heat moves very slowly through a solid body. As with an ordinary camera, the air is invisible. Thermal imagers will see completely through smoke, mists or sprays, which is one of the reasons why they are so useful for what they were designed to do. For this reason, a cold spot in the air will not show up in a thermal image at all. There is not enough mass to emit IR radiation.

Not all surfaces show their true temperature. Metals, for instance, appear dark and reflect mid-far-IR. Other surfaces that readily reflect mid-far-IR include glass, polished ceramics and stone.

Any temperatures, or even images, on these surfaces, in fact, are a reflection from another source. Imagine taking an ordinary light photo of a mirror and you will begin to see the problem. Such reflective surfaces may even reflect radiation onto surrounding surfaces, heating them up. Any reflective object could also reflect radiation directly into the thermal imager lens, possibly causing strange, false images similar to lens flare. Since mid-far-IR acts like light, the same kind of anomalies can occur as in ordinary light photos. Odd shapes can appear suggestive (like faces or figures) of paranormal phenomena. Given that the objects look completely different to their appearance in light photos, this can be particularly problematic. So what may look like a dark ghostly figure in a thermal image may just be a tall, cylindrical metal object. As in ordinary cameras, images can be out of focus in thermal imagers. Also, since mid-far-IR has a longer wavelength than light, and images will always appear fuzzier compared to ordinary video.

Overall, this means that you should not expect too much detail in thermal images. Any small anomalies are probably nothing but artifacts. Because mid-far-IR ignores small particles in the air, at least you won’t see dust orbs! Because of these problems, it is recommended that another video camera (night vision), pointing at the same scene, should always used in conjunction with thermal imagers. In this way it should be possible to check the identity of any strange shapes that appear in the thermal imager.

As with laser thermometers, the temperature reading depends on the emissivity of the objects being imaged. This is a property that varies from object surface to surface. Since the emissivity will typically vary from object to object in one image, it means the temperatures shown cannot be completely relied on to be accurate.  What looks like a 20 degree difference between two objects may only be 5 or 10 degrees. A thermal imager can give a reasonable picture of surface temperatures but if accuracy is important, you will need a thermometer as well. Surface textures will also affect the reflective properties of the same materials example; you have three pieces of granite. One is smooth as glass, one is heavily textured and the last is chipped and extremely rough. Side by side in a thermal imager they will look like they are different temperatures even though they are exactly the same temperature. This is because of the reflective properties of the different surfaces.

As with any instrument, you should understand what it does, how it works and its limitations. Unless you clearly understand the science behind a thermal imager and what it is measuring, claiming a paranormal anomaly from a thermal camera would be unwise. Most people think you just power up the device and start recording, Thermography  is a very specialized field that takes many months if not years to receive certification, there is a simple reason for this, not all is what it appears to be when you are using these tools, it is not a visible light camera where you just turn it on and what you see through the lens clear and simple.

I will try to sum this all up, to show you why a thermal imager does not and will not do what all the paranormal reality shows say they do. Consider this.

1) If a FLIR camera could detect paranormal activities, don’t you think the manufacturers would market this fact? They don’t, they understand the limitations. If they could detect such things they would win the Nobel Prize.

2) Thermal imagers cannot see through glass, it only sees the surface temperature of the glass itself, and any reflections. Therefore anything seen moving on a pane of glass is simply a reflection of thermal energy from another heat source, like a real person.

3) Look at the photos below. If a thermal imager could see the temperature of the air (which is what you would have to do to detect a spirit, based on current hypotheses), ponder this.

We can roughly determine the ambient temperature of the environment by looking at the color key to the right, it appears to be around fifteen degrees C.

If it truly can see air temperature why isn’t the entire screen covered with the color of the ambient environmental temperature on the color key?  If it is thirty degrees C, why isn’t the entire screen blue? Because it simply cannot see the air temperature, no matter how hot or cold the air is. The air is not dense enough to emit infrared radiation. Therefore it cannot detect a cold spot moving through the environment.

One of the things I have noticed on Paranormal TV shows is that when the thermal imagers first started showing up, any reflection or motion was labeled as paranormal, however there was never any documentation of a “cold” figure moving through the environment. The shows didn’t want to give up on the new eye-candy gadget, so now they are seeing and labeling “hot” targets as paranormal. So what is it? Are ghosts hot or cold? Or is it whatever fits your agenda at the time?

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