Is There Anything That Occupies Space but That is Without Mass?

Most recent answer: 10/08/2011

Q:
Is there anything in nature that occupies space but that is without mass?
- Udaybhanu Chitrakar (age 65)
Kolkata, West Bengal, India
A:
Not that I know of.  
Even things that have zero rest mass, such as photons, have some energy and you can always define an 'equivalent mass' ,  mequiv=E/c2 which affects and is affected by gravitational fields.  The bending of starlight that passes nearby the sun is a well measured and predicted by the theory of  General Relativity.

LeeH

(published on 10/08/2011)