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Name: Hennie
Status: student
Grade: 9-12
Country: South Africa
Date: Fall 2011
Question:
I have been having some issues with the definitions of matter and energy.My textbook defines matter as anything that has volume and can be observed by our senses...what about odourless gasses? What about dark matter? What about the blind? Linus Pauling again describes matter as all forms of mass-energy moving at velocities less than the velocity of light...this seems more accurate but I am not completely sure what exactly mass-energy is...is it a 'mixture' of mass and energy? Is it mass that can be converted to energy?
Replies:
Usually, physicists say matter is anything that has mass. This is problematic on the incredibly small scale, but at the size of pions and larger, this holds true.

As for energy, the definition is: a conserved quantity that flows when there is a change.

According to Einstein, the relationship between the two is expressed by: E = mc^2

---Nathan A. Unterman

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