I wish there is an affordable instrument to measure paranormal, abnormal and normal entities. Such gadget would prove we are all living in the same dimensional space. I doubt there is inter-dimensional space. Not able to see the entities does not mean there exists inter-dimensional space. The simplest explanation is that our body sensory is not able to sense or pick up the energy radiated at certain resonances or frequencies. We cannot see electromagnetism but it is there. in scientific sense, EM should be changed to PEM or Particled Electromagnetic which covers light, electric and magnetic fields. Now we can make sense of our surroundings.
Our eyesight is able to sense PEM between 350nm-700nm. Our body is able to sense heat radiation near 0.8-1.0um. The spectrum of PEM is so huge. Thermal imager operates between 0.8um-5um giving false color translation of the spectrum division thus giving color to sight of different temperature region in which red that carries more heat near 0.8um and blue the ambient temperature near 5um when there is no heat radiated. We have PEM sensors between 0hz - 200GHz although RF spectrum covers until 300GHz. We have sensors to detect below 100nm to 10um. The rest of the spectrum requires new sensor technology to be developed covering wider band. We also need to cover false color division for image mapping to make sense of PEM energy readout.
There is a theory that counters "black hole theory" that states black hole in space absorbs all light because of large gravitational pull in the center of galaxy. The theory counters that something is not there does not mean it does not exist. We don't have the sensor technology that senses black hole resonance. Thus on the image of false color translation beyond the boundaries of the sensor band is given black.
Most probably our Creator has put some spectrum that is beyond our technology capability. PEM sensor responses on specific spectrum band through material resonance. Different materials response to different resonance that translates into electrical signal that allows us to detect the PEM radiated by the entities. Without this capability and technology we get black or zero on our scope.
Now that's the simplest explanation after spending more than 20 years in the field. The so-called inter-dimensional entities are particle matters that are able to penetrate objects. This has been lab proven. While humans and other living objects are solid matters. We all live in the same dimensional space. So the inter-dimensional entities are not inter-dimensional beings but we don't have the sensors to see them by our eyesight.
But there are powerful ultra wideband sensors that have been and being developed that could easily detect any inter-dimensional entities radiated energy. Some of the sensors have been put into space monitoring outer space entities rather than inter-dimensional entities back on earth. These sensors cost hundreds of millions to make.
There is some low cost instrument which has the capability to detect PEM spectrum between 0.8 to 5um. The instrument is high-end thermal imager and can cost a whopping USD20k per unit with very small viewing image translation of 4x4 cm with short range detection to about 3m. The instrument cannot do many functions except detect and record thermal variation and presence. If paranormal investigators could invest on expensive DSLR with night vision capability from Canon or Nikon, then this quality thermal imager used by millitary, utility and oil companies would be handy and record true presence of the inter-dimensional entities. Why not make your search for paranormal worth for once rather than searching a needle in the haystack.