Intergalactic Voyages

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Far beyond our Moon and Mars and the other planets is our greater galaxy and its billions and billions of stars. And yet it is but a flyspeck compared to the enormity of the Universe beyond. Could we every voyage to these distant galaxies?

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Credits:
Intergalactic Voyages
Episode 385, March 9, 2023
Produced, Written & Narrated by:
Isaac Arthur

Editors:
Darius Said
David McFarlane
Briana Brownell

Graphics by:
Jeremy Jozwik
Ken York
LegionTech Studios

Music Courtesy of
Markus Junnikkala, “Always Tell Me The Odds”
Sergey Cheremisinov, “Sirius”, “The Signals”
Stellardrone, “Red Giant”, “Between the Rings”,
Miguel Johsnon, “Far From Home”, “So Many Stars”
Aerium, “Fifth Star of Aldebaran”

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35 thoughts on “Intergalactic Voyages”

  2. Would the aluminum tunnel also emit thermal radiation that would also blue shift and also slow down a ship? Does the aluminum need to be at absolute zero to not emit and not slow a ship down?

    Excellent episode and very cool concepts always, thank you!

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  5. I just imagine what you'd be able to do with readings of the CMB and CGB from a bunch of different galaxies' POV. Would take a long, long time to harvest the data unless FTL; but what an impressive thing. Multi-millions of years of trillions symbolized in a map.

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  9. This channel goes great with Fraser Cain. Arthur is imaginative and inspiring while cain is pragmatic and informative. They go together like a drink and a snack.

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  12. You have to realize when you say you think FTL is impossible, they used to think airplanes were impossible. My hunch is that the R&D time for FTL is in geologic time, and so no civilization has had the time yet to invent it. Also, FTL is likely something this is invented, rather than discovered: it's not possible, but it can be made possible.

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  15. I’m asking the space YouTubers I follow because of a thing that popped into my head re the structure of very ancient galaxies being more developed than expected when viewed by JWST.

    Would the flow of time not have been altered by the mass of the universe as it expanded in the Big Bang. Space expansion is not limited by the speed of gravity/light but extreme gravity does alter the flow of time (time dilation). So could there have been a time differential that would occur as the bang/expansion happened and the time and everything else caught up?

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  17. We might see artificial beings in our future, which begin to feel bad and even get very sick, if they are disconnected from the internet and their social groups for too much time.

    If and when we can create artificial lifeforms, or even if we as a species can further evolve into more cyber technological beings, space would get so much more accessible that the blue marble could finally expand into interstellar or even intergalactic space with ease.

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  19. Thanks, Isaac, for a thought provoking episode on a big topic.

    There is another way to travel between galaxies that you didn't mention. Look for technosignatures in distant galaxies – or even just biosignatures if the galaxy is distant enough – and include the blueprint of your ecosystem along with those of the colonists with your initial "hello" message. Of course you can only reach galaxies that are already occupied, and you will be relying on the unconfirmed ability and willingness of those occupants to both receive your message and act on it. And it also depends on overcoming philosophical hangups surrounding the distinction between "copying" and "teleporting". But you could shave hundreds of millions of years off your travel time, and it may indeed be the only way to reach some of the more distant parts of the universe.

    I only know of one sci-fi novel where this is used as a method of intergalactic travel – and I wrote it.

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  21. This is the first time in forty years I've seen an understandable synoptic description of the galactic neighborhood. Add my congratulations and THANKS for your service.

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  22. What is the nature of the potential? There potential through cooperation and what? You spread an ethic and it has a trade component. Essentially how to be a democracy which is prone to want to cooperate with sentients living in other systems. If Earth is the land of Abiogenesis for all life in the universe, it is also a familial relationship originating from Earth which facilitates interstellar cooperation and trade. People will be able to observe and interpret whether the covenants are kept! When the universe was hot and dense enough to essentially be a star, there might have been significantly denser areas where the trace amount of heavier elements were created. Seems like we have a direction to take the economy. More galaxies than I thought we'd reach!

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  23. so relative mass? so E=mc² turns into F=ma?

    what about our speed that we've already got from the orbit of the solar system and the orbit of the galaxy?

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  30. Isaac you know you've been promoted on Youtube and elsewhere because your subject is positive and the future is always bright- even while the world is in serious trouble and of course nothing of what you discuss is happening. Intergalactic colonization is interesting but it's available on your channel because it's a distraction from reality- those groups responsible for and benefiting from the international mess are your friends…

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  32. Clearly one is entitled to ones own thought processes and opinions, but, how can you think we will never… ever have FTL? With all respect, it's just an ignorant statement celebrating ignorance. For a Neanderthal to state they don't think we will ever be able to reach the moon would be less ignorant, due to the fact of how much WE have seen that was once thought impossible being achieved or proved, clearly possible today. Keep in mind, that's going back a million years at best… You're talking billions to trillions here, hehe!

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  34. Some things said here are likely inaccurate based on recent work cosmology is a bit of a problem in this sense as there is a golden cow model to which any evidence contrary to their expected model is screened out by peer review resulting in one of the worst examples of confirmation bias in all of academia since positive psychology movement. Most of these can be traced back to long held assumptions largely made for convenience in the days before electronic computers which are subject to some serious cases of confirmation bias ultimately because *in general the connection between redshift and distance is always model dependent*.

    Thus if you treat redshifts as mapping to a specific cosmological distance in any direction you are automatically implicitly selecting a model. Ergo such methods will always reproduce a homogeneous and isotropic distribution regardless of the actual data. What would the error for such a judgment look like well you would measure a net expansion in all directions but with varying magnitude depending on the initial sample basically exactly what we observe with dark energy and the Hubble tension.

    Now this alone doesn't mean that an incorrect model choice is responsible for these discrepancies but we can test this assumption thanks to the discovery of the CMB dipole. Contrary to what gets conventionally taught we haven't known the nature of the CMB dipole it was just assumed to be kinematic in origin as if it was purely kinematic then there would be no need to adapt or change their underlying model. However thanks to work of Elis and Baldwin 1984 it has been shown that we can actually experimentally test this as for their model to remain valid the dipole must be purely kinematic in origin i.e. 0 cosmological component, thus if you can show there is a nonzero cosmological component you can falsify this assumption for the entire observable universe but to test this you need a large sample of cosmologically distant sources in excess of a million such sources all over the sky. The actual distance or redshift of these sources is irrelevant so long as they are distant as we only need to check if the two dipole match or not. This was finally tested in 2021 thanks to work by Nathan Secrest et al which showed that there is a factor of 3 times difference between these dipoles which gives a whopping 4.9 sigma statistical significance or a 1 in 2 million chance of being a statistical fluke. However now follow up work has only strengthened the significance of the dipole discrepancy well above 5 sigma such that we now have falsified the cosmological principal to 5.7 sigma by showing that the CMB dipole and a dipole constructed from millions of quasars across the sky do not match and thus the CMB dipole can not be purely kinematic in origin so the cosmological principal can not be valid for the observable Universe.

    This has major underappreciated significance as work has previously shown that throwing out the cosmological principal in our observable universe is enough to completely eliminate the need for "dark energy" as such an effect is a natural consequence of gravity in any sufficiently large expanding universe according to the general approximated mathematical formalism of the Einstein field equations. In this context while the expansion as a whole of the universe can only ever accelerate as a consequence of the unequal rate of experienced time and thus expansion in any part of spacetime. This distortion of time is directionally dependent in both space and time and thus causes the acceleration of space in any location to be uniquely dependent on the past history of that region (i.e. its past light cone cross section). Incidentally this is the total opposite of the cosmological principal where the metric at all points in spacetime is uniquely determined for all possible elements of spacetime. This has its own fascinating implications particularly in the domain of quantum gravity but that is a topic for another day

    Anyways for this subject this context means that no not all of the universe is racing away from us faster than light, instead there appears to be a cosmological dipole which distorts the distribution of matter. Much of this stuff is racing away faster than light however we are on the periphery of a vast basin of objects where the relative rate of expansion between them is slowing down over time corresponding to the "Great Attractor" but extending far deeper into the past i.e. many giga parsec scales at the minimum. In this picture the simplest fit to observations appears to be that most galaxies including most "satellite" galaxies to the Milky Way Andromeda the Triangulum Galaxy and the Large Magellanic Cloud(which is considerably more massive than the stellar mass estimates indicate 10^11 solar masses,(between 1/10 to 1/3 of the Milky Ways total mass) with about a dozen satellites of its own if I remember correctly, are at rest with respect to the larger universe of unbound objects i.e. they are in free fall with no orbital trajectory. Also thanks to combining other observations with GAIA astrometry data on other local group galaxies(GAIA wasn't designed to do this but it works if you account for them being extended objects) the local group seems to have formed very recently i.e. only in the last few billion years at the earliest.

    Moreover if we want to try reconciling this data with simulations of the general unconstrained Einstein field equations while most of the universe is racing away the decreasing redshift(a.k.a. blueshift subtracting from a redshift) in some regions appears to look like what we would expect in the general inhomogeneous Einstein field equations in accordance to the No big Crunch theorem proved by Matthew Kleban and Leonardo Senatore in 2016 which shows that for the Einstein field equations to be internally self consistent for all possible choices of initial conditions. If you want further insight this proof which is shown using a proof by self contradiction shows that for any sufficiently large initially expanding metric the net direction of change in volume can never reach an inflection point or flip at least not with out causing irreconcilable self contradictions

    Thus an abbreviated summary might be that the metric actually appears to self quantize, i.e. there should exist an imprinted minimum gravitational contribution between any two bits of information, when conservation of information is applied to the Einstein field equations thus letting us trivially obtain Bells inequality and a form of the ER=EPR conjecture as the criteria for any solution to the Einstein field equations to be internally consistent for any and all valid choices of initial conditions, in essence its Noether's theorem linking information conservation and internal consistency i.e. causality where space is in essence an emergent construct from mathematical relations between elements in an array. Or in essence space arises as a consequence of the metric which is itself the path integration sum (i.e. by principal of least action) of all possible bits/qbits basically what we call quantum entanglement is quantum gravity else information is not conserved and causality is violated.

    Given that one tiny change or really just dropping an assumption can give you so much physics from first principals for so little conceptually why hasn't it been obvious? Yes it means you have to solve the full nonlinear system of equations every time, but we already have to do that in Magnetohydrodynamics/plasma physics and the Naiver Stokes equations.

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