The universe doesn't expand into anything. No additional points of space are added -- whether finite or infinite, the universe is best modeled as a continuum (attempts to model space as discrete all seem to have problems) which means it has an uncountably infinite number of points. The expansion of space simply means that distances between any two given points increase over time.

Its like having an infinite Cartesian coordinate plane, then scaling it up by a factor of 2 and asking "what did it expand into?" It didn't expand into anything, it just scaled up by a factor of 2, that's all.

It hasn't been established that the universe came from the single point. That is still speculative, and there are numerous ideas, but not enough data to choose which (if any) are correct.

We know that the universe was originally very very hot and very very dense.

We don't know if it came from a point, or from another universe that collapsed, or if it just gets asymptotically smaller forever back in time.

Imagine the universe as an infinite grid. Now, if we reduce the space between each line to 0, the universe becomes a point. But it still has an infinite number of divisions, it's just that it's infinite * 0.

No matter how small an increase you make, adding anything to that zero instantly gives you infinite, so yeah.

Also thinking of it as an infinite grid might also help you conceptualize what it means for the universe to "expand". It's not expanding into anything, it's already infinite, it's just that the space between the demarcations are getting bigger.

Also thinking of it as an infinite grid might also help you conceptualize what it means for the universe to "expand". It's not expanding into anything, it's already infinite, it's just that the space between the demarcations are getting bigger. If the Universe is infinite then is always has and always will be.

Celestia - Real-time space simulation that lets you experience our universe in three dimensions.

ehtim (eht-imaging) - Imaging, analysis, and simulation software for radio interferometry.

KubOS - Open source software stack for satellites.

Akassh Systems - Focused on developing and supplying the next generation of extreme bandwidth, hyper-efficient communications gear for space satellites.

Astroquery - Contains a collection of tools to access online Astronomical data.

RussianSpaceWeb - News and history of astronautics in the former USSR.

Awesome Space - List of awesome space-related packages and resources.

The Orbital Index - Curated space news and links. Weekly, brief, and technical.

Space Search - Search engine for space objects. (HN)

100k Stars (HN)

Space Engine - Universe simulator. (HN) (HN 2)

Fermi paradox: why haven’t we found aliens yet? (2018) - New paper on the Fermi paradox convincingly shows why we will probably never find aliens.

AstroWright - Astronomy and meta-Astronomy by Jason Wright.