Spiders

Spiders are either manifestations of Shadow Beings from the 50th Dimension or an example of mass hysteria.

Mass Hysteria Theory
It is thought that spiders are a phenomenon whereby one or more individuals experience an imaginary threat. A form of hysteria in which an imaginary small creature is a danger to them. The phenomenon can be 'contagious' with the observer able to alert and convince others of the spiders existence. Observers may or may not become visibly scared but in almost all cases will be left with a sense of dread or uneasiness.

Shadow Being Theory
Stephen Hawking more recently theorised that perceiving a spider is caused by the brains inability to comprehend the 50th dimension and the true power of the Shadow Beings.

Those who claim to have seen a spider can sometimes become fearful and even panicked. Despite observers later describing the spider as being relatively small in size (very often only a few centimetres or less) at time of first perceiving the spider a person may describe the spider as "huge" or "massive". Hawking argues that this is the brain trying to comprehend something that is in fact far larger than the human brain is capable of perceiving.

Spider Web
Spider web is a phenomenon associated with spiders. Spiders Webs can be perceived with or without spiders. The phenomenon is more common in undisturbed areas, an observation for which there is no satisfactory explanation.

Hawking theorised the webs are our perception of the fractures between our dimension and that of the Shadow Beings and that the Shadow Beings prefer to enter our dimension undisturbed. Theories for the reasons the Shadow Beings want to remain undisturbed include:
 * The Shadow Beings are peaceful observers who are aware of the anguish they can cause lesser dimensional beings.
 * The Shadow Beings are refugees, seeking shelter in our dimension and hiding from other inter-dimensional beings.
 * The Shadow Beings that enter our dimension are spies or scouts who are covertly collecting information to prepare for an inter-dimensional invasion.
 * The Shadow Beings are inter-dimensional predators and are looking for lone humans separated from others.