So, what we are seeing, is actually the ray of light reflected from the objects. As the orientations of these reflected rays form different shapes, our brain can recognize the object’s shapes. When the reflected rays are of different frequency the object’s colors are sensed as different. Our brain is trained to sense the rays of different frequency with the different colors. It identifies them as different colors.
Infrared rays based cameras can detect the objects without the presence light. They can identify the object shapes in darkness. But we can see those objects when we brighten the identified objects with the light source.
Now let us have a look at the electro magnetic spectrum. This spectrum has various bands of waves identified with the range of frequencies (inversely wavelengths). The light band is one of these that we are living in. We can say that, we are the creature, living in light band spectrum. Nothing is visible to us in the other bands of the electro magnetic spectrum. We are using rays of other bands like x-rays, Microwaves, radio waves, infrared rays etc for various purposes. We have studied the effects of these rays passing through different objects. We know x-rays can pass through the objects; microwave can heat the water molecules etc. But we are unable to see what is there in this spectrum with our eyes.
Having said this, we can come to a conclusion that our eyes cannot see beyond the light band spectra. So now the question arises is that, there a life in these other bands like in light band? How to sense the objects that are pertaining to these spectra? Whether this universe looks different in different bands of electro magnetic spectrum?
Yes. This universe appears different in different bands of spectrum. Hence there may be life in other bands not visible to us. This can be stated hypothetically.