Back to Home

Blackholes2 Forum Message

Forums: Atm · Astrophotography · Blackholes · Blackholes2 · CCD · Celestron · Domes · Education
Eyepieces · Meade · Misc. · God and Science · SETI · Software · UFO · XEphem
RSS Button

Home | Discussion Forums | Blackholes II | Post
Login

Be the first pioneers to continue the Astronomy Discussions at our new Astronomy meeting place...
The Space and Astronomy Agora
The Metric As The Field

Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response To
Posted by pmb on February 24, 2000 13:12:00 UTC

One has to be careful when using the term "mass" when speaking about light. The gravitational field created by light is (while more complicated than a particle) produces twice the acceleration on particles that would normally be expected from m = E/c2. Light, when acting as a source of gravity, is said to posses an active gravitational mass (i.e. the mass that acts like the source of gravity). When light is responding to gravity then that property is called the passive gravitational mass.

The statement In GR mass almost always means the m in : m2c2 = gmnPmPn. is incorrect. If the mass refers to the source and is not otherwise qualified then they mean mass-energy (i.e. integral of T00) [See the definition for "M" in MTW page 452 Eq. 19.14]. If the mass refers to the mass of an object moving in the field then they mean rest mass (however they usually quality it at least once).

re = Otherwise for extended bodies, "system mass" is useless. - Not if it's the source of gravity. - MTW page 452.

re - If we restrict ourselves to using ordinary three component vectors in a SR revision of Newtonian mechanics it turns out the equation F = ma doesn't hold true anymore. ---

See

Follow Ups:

    Login to Post
    Additional Information
    Google
     
    Web www.astronomy.net
    DayNightLine
    About Astronomy Net | Advertise on Astronomy Net | Contact & Comments | Privacy Policy
    Unless otherwise specified, web site content Copyright 1994-2021 John Huggins All Rights Reserved
    Forum posts are Copyright their authors as specified in the heading above the post.
    "dbHTML," "AstroGuide," "ASTRONOMY.NET" & "VA.NET"
    are trademarks of John Huggins