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Does energy have mass? by Jim Grozier STS WIP seminar 23.2.12. E = mc 2. [1]. [2]. “…matter and energy are really different forms of the same thing. Any mass has an associated energy and vice versa”.
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Does energy have mass? by Jim Grozier STS WIP seminar 23.2.12
E = mc2 [1]
“…matter and energy are really different forms of the same thing. Any mass has an associated energy and vice versa” “This formula suggests that tiny amounts of mass can be converted into huge amounts of energy”
m1 m1 m2 m2 Conservation of Momentum and Kinetic Energy u1 u2 v1 v2 m1u1 + m2u2 = m1v1 + m2v2 ½m1u12+ ½m2u22 = ½m1v12 + ½m2v22
p = mvg E = mc2g p = m0vg E = m0c2g p = mvg E2 = p2c2 + m2c4 p =mvg “interconvertibility” p = mv E = mc2 m =m0g “concomitance” p = (m0g)v E = (m0g)c2
“It is not good to introduce the concept of [relativistic mass] of a moving body for which no clear definition can be given. It is better to introduce no other mass concept than the `rest mass’” Einstein, letter to Lincoln Barnett, 19.6.48, in [4]
“If you could do the measurements to one part in a trillion …” Susskind [5]
m2c2 = (p0)2 – (p1)2 m2c2 = (E/c)2 – p2 m2c2 + p2= (E/c)2 m2c4 + p2c2= E2 m2c4 = E2 [6]
“strictly speaking measuring rods and clocks would have to be represented as solutions of the basic equations (objects consisting of moving atomic configurations), not, as it were, as theoretically self-sufficient entities” Einstein, Autobiographical Notes, in [7]
“As science finds a very well-defined, narrow focus on certain problems, it has to neglect other problems – forget about certain questions, even certain facts, certain ways of looking at nature. My personal view about the mission of the history and philosophy of science is that we ought to be in the business of picking up all those things science drops as it goes on its triumphal march.” – Hasok Chang, January 2012
References: • Ian Sample, “Kindle makes for heavy reading”, Guardian 2, (27.10.11) • Hans C. Ohanion, “Physics”, Norton (1992) • New Scientist 10.12.2011, page 44 • Lev B Okun “The Concept of Mass”, Physics Today, (1989) • Leonard Susskind “The Black Hole War: My Battle with Stephen Hawking to Make the World Safe for Quantum Mechanics”, Little Brown & Co (2008) • Space, Time & Cosmology, Unit 7, Open University (1997) • Harvey Brown, “Einstein’s Misgivings about his 1905 formulation of special relativity”, European Journal of Physics26 (2005), S85-S90 • “Advancing Physics”, Institute of Physics (2000) • Max Jammer, “Concepts of Mass in Contemporary Physics & Philosophy”, Princeton (2000)