(urth) Travelling North aka miscellaneous thoughts on Wolfe

[Gerry Quinn]

From: "Jeff Wilson" <jwilson at io.com>
> On 6/9/2010 10:38 AM, Gerry Quinn wrote:

>> Secondly, the 'tacking' method of travelling faster than the wind works
>> for sailboats. But the analogy between wind and light radiation doesn't
>> hold up because light does not exert pressure in directions orthogonal
>> to its direction of travel, as moving air does.
>
> That's not entirely correct; if the light is reflected at an angle, it 
> imparts momentum at an angle normal to the reflecting surface. For example 
> if light traveling due north strikes a mirror facing SW and is reflected 
> to the west, the mirror is pushed NE. This sort of thing really happens, 
> and produces a measureable effect on natural and artificial satellites 
> _over_a_period_of_years_.

Yes, but this is different from the 'airfoil' mechanism that can propel a 
boat faster than the wind, and which is not available in the case of light. 
That said, I think I was wrong to place so much store in this, as light also 
has comensating advantages - unlike air, it will not necessarily resist 
objects that are already in motion relative to it

There still is the issue of accelerating *past* the speed of light, however, 
which applies to all similar FTL mechanisms.

- Gerry Quinn
.