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3
votes
1answer
33 views

Why is specific impulse measured in seconds?

Specific impulse is usually defined as: $$I_{sp} = \frac{F_T}{\dot m ~ g_0} $$ This comes out in seconds. I interpret it as follows: If I want $F$ Newtons of thrust, every second I must burn a ...
6
votes
0answers
390 views

Does positronium have a stable crystalline phase?

This is a long shot, but while the 100YSS conference is going on at Houston, i haven't been able to get a grip on myself and think in other, more mundane and short-term rewards as normal people do. ...
5
votes
0answers
257 views

Mirrors and light beam divergence technology limits

There are many applications for orbital space mirrors in astronomy (better telescopes) and space propulsion (solar power for deep space probes), but this is limited by the minimum beam divergence ...
3
votes
0answers
91 views

positronium BEC stability

After reading this article regarding Positronium BEC formation (for lasing purposes), there is a mention in there regarding Ps "up" atoms not annihilating with "down" atoms, the article is pretty ...