Well distance does reduce the number of photons per second that a given sensor with area of X can detect. Lets start with black body radiation. An object that is at equilibrium with it's environment gives off photons of total energy equal to the total energy of all energy being asborbed. An object in intergalactic space and has been there for 100 billion years, will asborb the energy of all the photons that it's surface captures plus all of the nutrinos that it's bulk mass captures. In addition it's surface may be reflective, or not so much. So even this object at .00001K still will bounce photons, it's gravity will bend photons that pass near, and give off black body radiation, as well as block photons. However here is the rub, How far away is the sensor, how much area does it have and what is the minimum photons per second that can result in a detection? My Mk 1 eyeballs have a very small sensor area, and require a lot of photons per second, to establish a detection. I am totally sure that my Mk 1 eyeballs have never reported seeing that 1m rock floating somewhere between the Milky way and Andromada galaxies. Therefor, for that set of object, distance and sensor, indeed that rock is stealthy.
The next thing is how usefull is this detection? What is the purpose of the detection, and what is the response time needed. Detecting the 1 m rock in intergalactic space, EM radiation from that rock took somewhere between .5 and 50 million years to reach earth, we had to wait 20 million years to collect enough photons to establish that something is there. However the response time needed is the average lifespan of the civilizations we create. We cannot use the detection for our society fails to have enough time to detect it.
So given that I have established that we CANNOT see everything, let us agree that indeed some things cannot be detected due to not enough packets of energy over time. Now, what if we constrain the object to be something within the Heliopause of a solar system, it has internal environment maintaining 273 degrees K, and we have one month to establish a usefull detection. Further limitations is that it arrived at it's location via jump, thus creating an energy spike as defined in the rules. Now we need to know something about the sensor abilities of the society/civilization in that system. TL 0 with Mk 1 eyes are never going to detect any but the ones trying to be seen (Circumpolar orbit with million candle power strobe lights!). Glass lenses should be able to be created at TL 0, however not many will be made so sensor coverage will be sparce and the sensors are now Mk 2 eyeballs with lenses perhaps 100X the photon gathering ability.
So the tech level of the sensor and the society's ability to build stuff affect sensor sensitivity and coverage. TL 4 pop 4 will not have much sensor coverage compaired to TL 4 pop 8, So the primary sensor ability is a fuction of tech level and population. The no stealth in space folks would agree that the TL 15 pop A folks will have a much easier time detecting due to sensor technology and coverage. So the question comes down to just one of technology and scale verses technology, size, and distance. My thought here is that there will allways be a Technology*Size*Distance that will not be detectible within a given Technology*Scale*Time. Let's discuss!
The next thing is how usefull is this detection? What is the purpose of the detection, and what is the response time needed. Detecting the 1 m rock in intergalactic space, EM radiation from that rock took somewhere between .5 and 50 million years to reach earth, we had to wait 20 million years to collect enough photons to establish that something is there. However the response time needed is the average lifespan of the civilizations we create. We cannot use the detection for our society fails to have enough time to detect it.
So given that I have established that we CANNOT see everything, let us agree that indeed some things cannot be detected due to not enough packets of energy over time. Now, what if we constrain the object to be something within the Heliopause of a solar system, it has internal environment maintaining 273 degrees K, and we have one month to establish a usefull detection. Further limitations is that it arrived at it's location via jump, thus creating an energy spike as defined in the rules. Now we need to know something about the sensor abilities of the society/civilization in that system. TL 0 with Mk 1 eyes are never going to detect any but the ones trying to be seen (Circumpolar orbit with million candle power strobe lights!). Glass lenses should be able to be created at TL 0, however not many will be made so sensor coverage will be sparce and the sensors are now Mk 2 eyeballs with lenses perhaps 100X the photon gathering ability.
So the tech level of the sensor and the society's ability to build stuff affect sensor sensitivity and coverage. TL 4 pop 4 will not have much sensor coverage compaired to TL 4 pop 8, So the primary sensor ability is a fuction of tech level and population. The no stealth in space folks would agree that the TL 15 pop A folks will have a much easier time detecting due to sensor technology and coverage. So the question comes down to just one of technology and scale verses technology, size, and distance. My thought here is that there will allways be a Technology*Size*Distance that will not be detectible within a given Technology*Scale*Time. Let's discuss!