How does a creature evolve to become invisible to night vision goggles?

Question

I am wondering if a species might evolve to deceive human technology - in particular, a set of night vision goggles. I imagine it is either cold blooded or it has thick fur - which doesn't trap air - so that warm air pockets don't show up in the goggles. What evolutionary trait is required for such an animal to fool our night vision goggles?

Answer 1

It may interest you to know that some of the earliest animals on earth were largely invisible to night vision goggles in the first place, and that later animals have actually evolved to be visible in night vision. The secret, as it turns out, is to be cold blooded. We'll get to that, but first let's deal with camouflage...

To begin, we have to understand how night vision goggles actually work. There are two types of night vision goggles out there, some work via thermal imaging and others by image enhancement.

Image enhancement can be beaten by blending in with the background in terms of shape and texture, but this is no different to hiding during the day except you don't have to deal with colour as well. Just check out how well this polar bear can blend in, at least from a distance, compared to its infrared signature. Slide the vertical line on the picture from side to side and you see the bear disappear when the infrared slide is to the extreme right. So, if you can blend into the landscape during the day, there's a very strong chance you'll do so at night according to these types of goggles.

Now when it comes to thermal imaging goggles, it's important to note that the reason they work is because most of the animals (especially humans) we care about seeing in the dark are warm blooded. In biological terms, what warm blooded means is that the creature in question maintains a constant internal body temperature. In practical terms, that means that they can be active and alert even when it's cold, but at the price of a variable metabolism that requires more food in the cold to maintain the difference between the ambient temperature and their internal temperature. On the other hand, a cold blooded creature has an internal temperature similar to the ambient temperature, meaning that it only becomes active when it is warm out. This means it needs less food to survive, but the cost is that it's not as active in the cold meaning it can be caught by predators more easily during those times.

If you look at the snake in these thermal images you can barely see it. This is because it is the same temperature as the ambient environment, whereas all the mammals and birds are hotter than the ambient environment, especially during the night when it is cooler, which is why thermal imaging often works so well for night vision.

Ultimately, to make it harder, what you want is night vision goggles that integrate BOTH methods, so that your creature trying to hide is both cold blooded AND camouflaged to the environment. Can that happen? Sure. Arguably it already does insofar as visible light is only a very small percentage of the EMR spectrum meaning that the ultraviolet 'glow' of a spider web for instance is completely invisible to us. Polar bears can even be quite hard to spot on thermal imaging because they carry so much insulation to keep them warm in cold environments without having to eat so much, and certain insects are indistinguishable from leaves or sticks even during the day, let alone via night vision goggles.

All in all, the answer to your question is yes, but it gets 'harder' to do so depending on what else you want your creature to do. If you want it active at night for instance, making it warm blooded puts it at a distinct disadvantage as far as thermal imaging is concerned. If you just want it to sit still and be 'invisible', that is not interact with your begoggled humans, then just pick an animal out of the stock that Earth has already produced.