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Forum » SpaceEngine » Science and Astronomy Discussions » Dark Energy
Dark Energy
NeonDate: Sunday, 29.05.2011, 05:29 | Message # 1
Explorer
Group: SE team
Australia
Messages: 205
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Hey Tzion,

I know you have studied Physics for last 4 years. Maybe you could answer a question fo me. wink

Could you explain Dark Energy and how it effects the galaxies, and maintains the
voids between the galaxies?

Neon
 
SpaceEngineerDate: Monday, 30.05.2011, 22:14 | Message # 2
Author of Space Engine
Group: Administrators
Russian Federation
Messages: 4796
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It's been seven years, not four. smile

Dark energy is strange stuff from Einstein's equation of General Relativity. It was introduced to explain observations of distant supernovae. According to these observations, our Universe expansion is accelerating. So scientisits remember Einstein's Lambda term that he introduced to his theory for describing a stationary Universe (not expanding and not collapsing). Lambda term is the equivalent of global antigravity, or equivalent of matter with negative pressure, if you move this term to right ("material") part of equation. This leads to accelerated expansion of space-time for some models, or stationary for other models.

Dark energy does not affect galaxies, or clusters of galaxies, or voids betweem them. It is only a new property of space-time, which makes Universe expansion accelerate. It is distributed uniformly throughout space, so galaxies can't feel its influence.

We don't know why the universe expansion is accelerating. This might be due to some new type of field particles, due to new properties of space-time (like the modern interpretation, called Dark Energy) or simply due to mistakes in observations, or in its interpretation. I think the latter is right though smile

You can read more on Wiki: http://en.wikipedia.org/wiki/Dark_energy

*





 
NeonDate: Friday, 10.06.2011, 17:53 | Message # 3
Explorer
Group: SE team
Australia
Messages: 205
Status: Offline
Thankyou for that. Sorry I forgot to reply, I'd not looked in here for
a couple of weeks.

Well, that's the best explanation I've ever heard. Thanks Tzion. That
Albert guy was one smart fellow. This is why I asked you, because
trying to find out what physicists really think is very difficult online,
as mostly you get so many different answers, some informed, some
sort of dumbed down.

Much appreciated smile
 
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