What is the difference between Boost and Translation?

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Discussion Overview

The discussion centers on the distinction between "boost" and "translation" in the context of Poincaré transformations, exploring their definitions and implications in physics. The conversation touches on theoretical aspects of these terms as they relate to changes in velocity and position.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants assert that a "boost" changes an object's velocity, while a "translation" changes its position without affecting velocity.
  • One participant suggests that a boost could be interpreted as a change in position with acceleration, but others clarify that it involves constant velocity and no acceleration of the object.
  • A participant notes that a boost is often understood as a Lorentz transformation for a given velocity, emphasizing that it is a rotation-free transformation.
  • Another participant elaborates that in a translation, the coordinate systems have different origins without relative velocity, while in a boost, the final coordinate system has some velocity relative to the initial one.
  • Some participants propose a broader interpretation of "boost" as a change in acceleration, force, or power, but this is contested by others who maintain it specifically refers to a change in velocity.
  • A participant contextualizes "boost" in terms of spacecraft engines, explaining that it involves turning engines on to change velocity, which may involve varying acceleration during the boost period.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and implications of "boost" and "translation," with no consensus reached on the broader interpretations of "boost." The discussion remains unresolved regarding the precise definitions and contexts of these terms.

Contextual Notes

Some claims about the nature of boosts and translations depend on specific definitions and contexts, which are not universally agreed upon. The discussion includes varying interpretations of the term "boost" that may not align with traditional definitions.

suvendu
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As we face in Poincaré Transformation, there are boost and translational symmetry.What is the difference between these two terms?
 
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A "boost" changes an object's velocity. A "translation" merely changes its position.
 
Thanks for the reply. So basically boost is a change position with acceleration?
 
I always read "boost" as short for "Lorentz boost" and simply meaning the Lorentz transformation for a given velocity (speed and direction). For what it is worth, Wikipedia [1] seems to agree with this, with the addition that a boost is a rotation-free Lorentz transformation.

[1] http://en.wikipedia.org/wiki/Lorentz_transformation
 
suvendu said:
Thanks for the reply. So basically boost is a change position with acceleration?
No- with constant velocity
 
suvendu said:
Thanks for the reply. So basically boost is a change position with acceleration?

We're simply changing coordinate systems. No acceleration of the object is involved.

In a translation, the initial and final coordinate systems simply have different origins. There is no relative velocity between these two coordinate systems.

In a boost, the final coordinate system has some velocity relative to the initial coordinate system. The origins of the two coordinate systems often coincide at t = 0.
 
Thank you jtbell,Filip and Meir. :)
 
More generally "boost'" can be a change in acceleration or in force or in power.
 
More generally a "boost" can be a change in acceleration or in force or in power.
 
  • #10
Ajit hira said:
More generally a "boost" can be a change in acceleration or in force or in power.

No. As stated before, it's a change in velocity.
 
  • #11
Ajit hira said:
More generally a "boost" can be a change in acceleration or in force or in power.
Putting the term in context: Mostly, the engines of a spacecraft are off and acceleration from them is zero. Boost, involves turning them on, (often for a short time) which will change the velocity almost instantaneously (compared with the time period of the orbit). If you're lucky, the acceleration will be constant during the period of the boost but, for a long burst, the mass of the craft will be reduced and so the acceleration may well increase during the burst time.
It strikes me that the context of the passage where the term is used will give a clue as to the details of what is meant.
 

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