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........
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Einstein's Mass-Energy Equivalence
- Thread starter quasar987
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Discussion Overview
The discussion revolves around the notation and terminology related to Einstein's mass-energy equivalence, specifically focusing on the components of four-velocity and the metric tensor in the context of spacetime. Participants explore definitions and pronunciations of symbols used in physics.
Discussion Character
- Technical explanation
- Conceptual clarification
Main Points Raised
- Some participants discuss the meaning of the symbol \eta and its components, specifically \eta_{0,x,y,z}, which are identified as components of the four-velocity.
- There is a clarification that 'ita' refers to the metric, and u_{\mu} is the four-velocity.
- One participant questions the definition of a 'metric', leading to an explanation that it refers to the metric tensor g_{\mu\nu} in physics, and for flat Minkowski spacetime, it is represented as \eta_{\mu\nu}.
- Pronunciation of the symbol \eta is discussed, with variations noted between different languages and historical contexts.
Areas of Agreement / Disagreement
Participants appear to agree on the definitions of the symbols and their meanings, but there are varying opinions on the pronunciation of \eta, indicating some disagreement on that aspect.
Contextual Notes
Some assumptions about the familiarity with tensor notation and the context of spacetime metrics may not be explicitly stated, which could affect understanding for those less familiar with the topic.
- #2
dextercioby
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Who's ita_{0,x,y,z) ??
Daniel.
Daniel.
- #3
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As it often happens I found the answer to my question while typing it 
[itex]\eta[/itex] was for the proper speed... i.e. [itex]\eta_{0,x,y,z}[/itex] are the components of the four-velocity. What symbol do you use?
[itex]\eta[/itex] was for the proper speed... i.e. [itex]\eta_{0,x,y,z}[/itex] are the components of the four-velocity. What symbol do you use?
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dextercioby
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Ita is for the metric...[itex]u_{\mu}[/itex] is the four-velocity...
Daniel.
Daniel.
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What's a 'metric' ?
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dextercioby
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A distance,in mathematics (a metric space is a topological space with a metric)...Here,in physics jargon,it stands for the metric tensor [itex]g_{\mu\nu}[/itex] for spacetime and for the flat Minkowski spactime [itex]\eta_{\mu\nu}[/itex]
Daniel.
Daniel.
- #7
krab
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quasar: [itex]\eta[/itex] is pronounced like something between etta and ayta; not eeta.
- #8
dextercioby
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In Neogreek it is pronounced ITA (eeta,if u want to).True,in Anciant Greek it's ETA...
Daniel.
Daniel.
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