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Expert: - 7/31/2008


Question
Hello,

I was wondering, did Einstein say NOTHING could go faster than the speed of light (particles etc. included) or just that any object with mass like cars couldn't go faster than the speed of light?

Thankyou for your time and help,
Alice

Answer
Hello,

In his paper, 'Does the Inertia of a Body Depend on its Energy Content? (in Annalen der Physik, Vol. 17, 1905) Einstein basically showed that as a mass approaches the speed of light, its inertia approaches an infinite amount.

Consider a body of rest mass m_o and let is move at velocity v = c:

m'  =   m_o/  (1 - v^2/ c^2) ^1/2

Then if v = c:

m' = m_o/  (1 - c^2/c^2)^1/2 =  m_o/ 0  -> oo


So the mass m' (non rest mass) becomes "infinite", as does the inertia which is tied to mass (inertia is the property of resistance to change in position or motion). This is merely another way of saying that it would take all the mass in the universe to be converted into energy to attain a velocity of v = c.

Since all the mass in the universe would already be expended for such a feat, than exceeding that limit would clearly be impossible.

Hope this helps!

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Philip A. Stahl

Expertise

I specialize in stellar and solar astrophysics. Can answer any questions pertaining to these areas, the spectroscopic analysis of stars – as well as the magneto-hydrodynamics of sunspots and solar flares. Sorry – No homework problems done or research projects! I will provide hints on solutions.

Experience

Have published papers on the relationship between sunspot morphology and solar flares; discovery of SID flares related to this, constructed computerized stellar models; MHD research.

Organizations
American Astronomical Society (Solar physics and Dynamical astronomy divisions), American Geophysical Union, American Mathematical Society, Intertel.

Publications
Solar Physics, Journal of the Royal Astronomical Society of Canada, Journal of the Barbados Astronomical Society, Meudon Solar Flare Proceedings (Meudon, France). Books: 'Selected Analyses in Solar Flare Plasma Dynamics', 'Physics Notes for Advanced Level'.

Education/Credentials
B.A. degree in Astronomy; M.Phil. degree in Physics - specializing in solar physics.

Awards and Honors
Postgraduate research award- Barbados government; Studentship Award in Solar Physics - American Astronomical Society

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