Anyone who has spent any time considering the question of whether God exists or not has probably come across the inter-related terms omniscience and omnipotence. There is a third related term that does not seem to get nearly as much attention. Omnipresence. It is interesting to note that the idea that God is somehow present in a single location is shaky at best. In most instances that someone refers to God being present they are usually commenting on an emotional response to something that they then retro fit to their already established religious beliefs. Such experiences are generally in response to an event or circumstances, or even a delayed reaction.
Given that it is virtually impossible to establish an actual "presence" it is odd to think of an entity that can simultaneously be everywhere all the time, which is the basic principle of omnipresence. If God is an entity and does physically interact with us in some way then you would assume there would be physical evidence. There isn't. It would also violated numerous laws of physics for a physical entity to be absolutely everywhere all at once. The only materials science is aware of being capable of anything similar are sub-atomic particles. Such particles do have an effect on us but cannot be sensed as present in any practical way. It is rare that God is not described in terms that relate to a sentient being. It is hard to image that it is even remotely possible for a being that has the characteristics of sub-atomic particles necessary to be omnipresent could maintain the type of coherence necessary for a single entity to exist.
Basically, in physics the only things that might be capable of omnipresence cannot directly be perceived by human beings and is virtually impossible to have such a trait and still have a coherent body of any sort. There is no reason to presume that sentience, let alone a more advanced sentience than that of humans, can exist without a physical brain (the only known source for a mind). If omnipresence is a necessary trait of God, which it arguably is, then God would seem to be highly unlikely on this basis alone.