# What is the difference between Boost and Translation?

1. Apr 10, 2014

### suvendu

As we face in Poincaré Transformation, there are boost and translational symmetry.What is the difference between these two terms?

2. Apr 10, 2014

### Staff: Mentor

A "boost" changes an object's velocity. A "translation" merely changes its position.

3. Apr 10, 2014

### suvendu

Thanks for the reply. So basically boost is a change position with acceleration?

4. Apr 10, 2014

### Filip Larsen

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

5. Apr 10, 2014

### Meir Achuz

No- with constant velocity

6. Apr 10, 2014

### Staff: Mentor

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.

7. Apr 11, 2014

### suvendu

Thank you jtbell,Filip and Meir. :)

8. Dec 4, 2015

### Ajit hira

More generally "boost'" can be a change in acceleration or in force or in power.

9. Dec 4, 2015

### Ajit hira

More generally a "boost" can be a change in acceleration or in force or in power.

10. Dec 4, 2015

Staff Emeritus
No. As stated before, it's a change in velocity.

11. Dec 5, 2015

### sophiecentaur

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.