I mean, is it
change = gravity
change = expansion - gravity
<retracted> According to some calculations, it should in principle be possible to colonize the entire observable universe in less than a hundred million years. It's much too fast for the expansion to affect except marginally.</retracted>
The relative jump in difficulty from interstellar to intergalactic is much smaller than from interplanetary to interstellar.
Anyway, as others said, mere intragalactic (and intra-Local Group) travel is not affected by expansion in any way whatsoever.
[1] https://www.sciencedirect.com/science/article/abs/pii/S00945..., PDF at https://www.aleph.se/papers/Spamming%20the%20universe.pdf
The observable universe is ~93B LY - unless you're assuming FTL (and MUCH faster than light), I don't see how that's possible?
Interesting way to put it... This doesn't seem that accurate. With sufficiently advanced technology, many of which we already possess, we could expect to propel a minute spacecraft to a considerable fraction of the speed of light, and reach nearby stars possibly within the end of the century. Reaching the other end of the galaxy is a massive undertaking. It's a logarithmic scale at every step of the way.
Pluto is about 38 AU from Earth. Proxima Centauri is about 6.3 × 10^4 AU away (or about 4.24 ly), and that's roughly a 2 × 10^3 multiplication. The Milky Way is about 50000 ly in radius, and the Andromeda Galaxy is about 3 × 10^6 ly away. Going from interplanetary distances to interstellar, and thence to intergalactic, involves at least a 10^5 factor (give or take) at each step.
The idea that, given a million years of further technological development, intergalactic travel might actually be feasible, isn’t really that implausible. Far from certain, but far from implausible either.
And that’s the thing-a million years is a technological eternity, a rounding error in estimates of time to colonise the galaxy/the local group/the observable universe.
...what? That doesn't seem right, just from a really quick gut check it looks like the observable universe has a radius of 45.7 billion light years [0]. Even if the universe wasn't expanding nobody could get to everything any faster than that number of years right? Maybe you saw something that was talking about the local (Virgo) supercluster, which I think has a radius of around 55 million light years, so that sounds more like something that could be done on that timescale "in theory". But there are millions and millions of superclusters in the observable universe overall.
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> ...what? That doesn't seem right, just from a really quick gut check it looks like the observable universe has a radius of 45.7 billion light years [0].
I guess it depends on whose hundred million years you're talking about: the colonists' or those who stay home's. I don't know how to do the calculations, but it seems plausible that you could traverse the entire observable universe at near light-speed in 100 million years ship time.
At 0.995 c, the ship clock runs 10 x slower.
At 0.999 c, 22 x slower. Then if you push the turbo button to 0.9999 c, 71 x slower.
The fastest man-made object to date is the Parker Solar Probe, at 0.059 c.
[1] https://www.sciencedirect.com/science/article/abs/pii/S00945...
Also note that there isn't any "container" to fill up. It could well be infinite. It's just that we will be forever limited to a finite subset, even in theory.
At the very bottom. Weird how style guides keep putting important information like this in harder to reach places.
That said, I cannot wait for adtech to go the way of the rotary phone. Localized, private search indexes on phones with local AI interacting with them, only reaching out to the internet when necessary to update information, with hashes and checksums to minimize the number of updates needed for frequently interacted sites, and so on.
Google right now is hot garbage - most tiny competitors are far better, let alone yandex or kagi or the like.
"Prof Carlos Frenk, a cosmologist at the University of Durham, who was not involved in the latest work, said the findings were worthy of attention. “It’s definitely interesting. It’s very provocative. It may well be wrong,” he said. “It’s not something that you can dismiss. They’ve put out a paper with tantalising results with very profound conclusions.”"
https://www.theguardian.com/science/2025/nov/06/universe-exp...
For claims about how the universe works at scales and timeframes so utterly beyond anything testable, it's a little difficult to say this is credible at all - not dunking on the researchers, but in order to validate their conclusions, there's a whole chain of dependencies and assumptions you'd have to follow along with, and each of those things will be its own complex birds nest tangle of assertions, and I don't see how you can really say one way or another until you have a lot more information and a lot better Theory of Everything than we've got right now.
For what it's worth, for all the impact it'll have on anyone's life outside of academia, I'd say they're 100% correct and people should buy them free beers at their local pubs for at least the next year in return for explaining their ideas at length.
I don't think so. Deceleration does not imply recollapse. AFAIK none of this changes the basic fact that there isn't enough matter in the universe to cause it to recollapse. The expansion will just decelerate forever, never quite stopping.
AFAIK the previous models that all assumed that Type 1a supernovae were not affected by the age of the progenitor stars had no actual analysis to back that up; it was just the simplest assumption. This research is now actually doing the analysis.
Universe gong.
I'll set a reminder to check back at that time to see who was right.
If we subscribe to a theory of the multiverse, set theory, likelihood, and interaction driven evolution based on gradient type of fundamental laws. Locally changing. Obviously everything sharing a fundamental quality that is part of existence itself. But obviously there are sets, there is differentiation. But it is not created, the infinity of unconstrained possibilities exists in the first place and reorganizes itself a bit like people are attracted to people who share some commonalities or have something they need from each other and form tribes. Same processus kind of works for synapse connections, works for molecule formations, works for atoms... etc... Everything is mostly interacting data.
We could say that the concept of distance is a concept of likelihood. The closer is also the most likely.
Just a little weird idea. I need to think a bit more about it. Somewhat metaphysic?
I can say the same about forgnoz, which is something I've just invented that must exist by definition.
You'd need to try a bit harder to make existence actually inevitable.
A key point in the article. From what I understand, this is the main way we measure things of vast distance and, from that, determine the universe's rate of expansion. If our understanding of these supernovae is wrong, as this paper claims, that would be a massive scientific breakthrough.
I'm really interested in the counterargument to this.
Roger Penrose seems to be leaning/more convinced of the circular universe theory....
And of course, the people concerned with tracking near-earth asteroids are not connected in any way with cosmology.
while science might not have a definitive answer for everything, they distinguish from fact and theory.
Also this discovery does still is being explained with dark energy (albeit time varying …) so it still does not assume global energy conservation.
Because there is no shortage of 'crackpots' that have 'obvious' solutions to unsolved physics problems, and that want to publish papers about it.
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Edit: yep, The universe's expansion may actually have started to slow rather than accelerating at an ever-increasing rate as previously thought, a new study suggests.
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