Physical object

An object is usually meant to be defined by the simplest representation of the boundary consistent with the observations.

However the laws of physics only apply directly to objects that consist of the same collection of matter.

In modern physics, "extension" is understood in terms of the spacetime: roughly speaking, it means that for a given moment of time the body has some location in the space (although not necessarily amounting to the abstraction of a point in space and time).

The properties of an object are inferred by learning and reasoning based on the information perceived.

Abstractly, an object is a construction of our mind consistent with the information provided by our senses, using Occam's razor.

For a rigid body, the boundary of an object may change over time by continuous translation and rotation.

Also an object's identity is created at the first point in time that the simplest model of the system consistent with perception identifies it.

Inanimate objects generally lack the capacity or desire to undertake actions, although humans in some cultures may tend to attribute such characteristics to non-living things.

[3] In classical mechanics a physical body is collection of matter having properties including mass, velocity, momentum and energy.

In particle physics, there is a debate as to whether some elementary particles are not bodies, but are points without extension in physical space within spacetime, or are always extended in at least one dimension of space as in string theory or M theory.

Examples are a cloud, a human body, a banana, a billiard ball, a table, or a proton.

Other examples that are not physical bodies are emotions, the concept of "justice", a feeling of hatred, or the number "3".

In some philosophies, like the idealism of George Berkeley, a physical body is a mental object, but still has extension in the space of a visual field.