3 HN users recommended this explainer2 months2021–2024score 2
Years with an HN recommendation, 2007–2026
Cited in cosmology threads as an accessible visual explanation of the unreachable universe and its expansion limits.
Kurzgesagt explains why, even with science-fiction technology, most of the universe is permanently out of reach because of cosmic expansion and finite resources.
“See this excellent video for more detail” (HN, 2021)
This is forgetting to account for the accelerating expansion of the universe. Even if one were to depart from Earth today, traveling at light speed, 94% of the observable universe is already impossible to reach. See this excellent video for more detail: [this video]
Explains why most of the observable universe is unreachable.
I've been enjoying the kurzgesagt collection of videos[1] which discusses the same phenomena, and how we literally can never travel to large swaths of the universe. [1] [this video]
Explains why large swaths of the universe can never be reached.
I always appreciate content like this which is easy to digest but still inspires awe in the universe around us. Scrolling around the map and looking further and further back in time reminded me of this Kurzgesagt video [0]. It's crazy to think how much of the universe is lost to and unreachable by us. Kurzgesagt has a lot of great content (even if it's a bit cartoonish). I'm sure they get things wrong, but I feel like they make an effort to research the topic first. [0] [this video]
You would never reach your destination and at some point you would be stranded in dark space. This kurzgesagt video has some info on this topic.[1] [1] < [this video] >
Kurzgesagt on limits of travel in an expanding universe.
The video doesn't follow the timeline. The video and voice over is still displaying and explaining about white dwarfs after all the stars have burned out, including red dwarves. It looks pretty, but it's incongruous and doesn't fulfill what the title promises in that it doesn't follow its own time lapse. Here's one[1] that actually makes sense in only 9 mins, albeit without the trendy soundtrack. Here's a Kurzgesagt[2] that gets pretty close to the subject. [1] [link] [2] [this video]
Kurzgesagt video relevant to the end-of-time topic.
> Rather it's that the rate of expansion of the universe is accelerating, so that we're moving away from parts of it faster than its light can cover the distance to us. It will never reach us. It's actually even worse than that. Because of the accelerating expansion of the universe, over time the part of the universe that we can observe will get smaller, allowing us to see less and less of it. Eventually, all that we'll be able to see is our own local group of galaxies, where gravitational attraction will win out over the universe's expansion. However, this won't really be a problem for a few billion years. Relevant Kurzgesagt video: [this video]
Relevant to shrinking observable universe from accelerating expansion.
That rate is "only" approximately 68 kilometers per second per megaparsec. 68 kps isn't that fast (it's about the same speed as the Helios 2 solar probe) and a mega parsec is big distance (3.2M light years). Its that there's a lot of megaparsecs between here and there and the sum of all of those 68 kps is more than the speed of light. The relevant Kurzgesagt : TRUE Limits Of Humanity – The Final Border We Will Never Cross - [this video]
Relevant to recession speeds exceeding light speed.
Simply - yes. Furthermore, civilizations that arise in that era of the universe will likely have a different cosmology than what we are able to understand today. If you could only see the galaxy that you are in, you wouldn't be able to see galaxies that were forming shortly after the Big Bang, or be able to use supernovas in other galaxies to measure the scale of the universe. Kurzgesagt did a video on that - TRUE Limits Of Humanity – The Final Border We Will Never Cross [this video]
Covers how future civilizations see a limited universe.
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