Is the universe conscious? Well, parts of it certainly are! And those parts are learning about itself as a whole.
-But is there anything faster than light?
-Yes! Our thoughts. In my thoughts I can be on the moon instantly.
... on Earth?
You might feel like you're a speck floating above kilometers of deep dark ocean, but that's just your matter. If you think about your (our!) information, we're almost more like the water itself in our permeance -- or like some sort of aerogel -- compared to anything else floating in this thing :)
I get the sense that being in a room (which is always pretty small) makes the abstract claustrophobia feel more real.
Truth is I have never been able to describe that particular physical feeling, so maybe claustrophobic is not exact but perhaps a similar type of physical sensation/experience.
For me it’s actually very difficult to put myself in that state, it’s somewhere between extremely deep thought and meditation...I’ll go so far as to say even things I don’t necessarily believe in such as remote viewing and/or some type of outer body experience.
I’ll also add that while it’s not something I actively practice by any means ( and I otherwise engage in breathing exercises/meditation - mostly to help my running) I really like that uneasy feeling and find I can only maintain it for short periods.
It is always a very humbling sensation, which is good. No place for arrogance when you are nothing and mean nothing from certain scale of things.
I think it can be re-framed like a feeling of freedom and possibility. For instance, if you managed to live one million years and visit all the galaxy, you would have not even started.
Yes, several hundreds of people had already been in space.
Space travel could be the norm in the next few decades.
Man could terraform Mars in the next millennium, or conquer the milky way galaxy five million years later.
However, I still feel like "we're stuck forever".
One of the neat ideas it communicates is that the longer we wait, the less of the universe we can access:
Delay - Galaxies lost
1 million years ~ 0.02%
10 million years ~ 0.2%
100 million years ~ 2%
1 billion years ~ 20%
10 billion years ~ 80%
150 billion years ~ 99.9999997%
"For example, dropping matter into black holes via their accretion disks
converts 5.7% of its rest mass into light, which far exceeds the efficiency of the
thermonuclear reactions which power stars, and might be a much more efficient way
to gain access to the mass-energy stars contain (though it clearly comes with its own
"A related question is not how much matter (or energy) could be reached, but what is
the greatest amount a civilisation could secure in one gravitationally bound location,
so that it could be used for some unified long-lasting project during the time of
Maybe we can pinpoint where advanced alien civilizations would be based on an understanding of their energy needs.
Spoiler alert on Hubble Extreme Deep Field photo: "This image
thus spans the edge of our affectable universe, with most of the places it shows being
forever beyond our reach. "
I find all of this incredibly beautiful.
An ambitious civilization will figure out a use for whatever amount of harvestable energy is available. Computation, if nothing else. The paper is about upper bounds; whether any civilization can (or wants to) actually reach anywhere near them is another question for another paper.
For example the 'civilisations at the end of time' series https://www.youtube.com/playlist?list=PLIIOUpOge0LvHsTP5fm8o...
The light we see is old. It’s of interest for studying the science of bright old things but for anything contemporary it is useless. If you ignore our own star and count out the ancient starlight, the sky is completely dark to us.
It is as if we are searching for someone to talk to by rummaging through rocks, looking for fossils. It applies to humans too. Anyone we sent to another star would be gone for years. They would be physically gone, but fundamentally we just wouldn’t be able to talk to them at all for years on end.
Unless something about the speed of light changes, Earth and her inhabitants will always be completely and fundamentally alone.
Andromeda at 2.5m ly is a bit more of a stretch, but it's still a fairly short period in the history of life on Earth. It all depends on how long we think technological civilizations last on average. If they can reach sustainability it could be at least as long as their solar systems remains habitable, maybe hundreds of millions of years, even without interstellar travel.
Even sunlight is really old.
The photons from our own star, the sun, were produced 100,000 years ago. That's how long they take to make their way to the surface from center of the sun where the nuclear fusion occurs.
There's current projects that hope to launch small probes to the nearest start (under 5 light years away) at a few % of speed of light powered by large arrays of lasers. Assuming it gets attention and additional funding the probes will get bigger and of course sensors are continuing to improve per unit of mass.
With a better survey of the nearest star, plants, asteroids, comets, and magnetic field we'd have a much better idea for what to send next.
Assuming reasonable progress on fission, fusion, plasma drives, light sails, and related technologies we could look at accelerating on this ends and slowing down at the opposite end. Once we can send small probes they would work on building mirrors to help decelerate whatever we send next. Similarly on this end we could put more solar panels+lasers in orbit to help with launches.
If any of the planets looking promising it doesn't seem insurmountable to eventually send humans (or at least their DNA) to the nearest star.
Either way, the universe is unbelievably, vastly bigger even than the observable 90 billion light years we live in.
Apparently the universe originally (somehow) began as a point of infinite density and expanded outward from this point.
During this process, it would seem to need a defined size in order to be expanding at all. Even with the "blowing up a balloon" way of thinking of the universe, while the individual galaxies are growing further apart, the surface area is measurable (not infinite).
I am likely thinking of this incorrectly but I can't fit "infinite size" in with "expanding universe" in my head.
Unless these theories are incompatible, and to get infinite size you need the steady-state theory.
The big bang was an "explosion" of space itself. There was not previously empty space.
I am very familiar with all of this. My question was merely around the opposing concepts of "expansion" and "infinite".
Not infinite size AT the big bang. Infinite size of the current universe.
On the other hand if Roger Penrose is correct about Conformal Cyclic Cosmology, and cosmic inflation is false, then ultimately the universe will reach a state where scale ceases to matter and it will become mathematically indistinguishable from a hot dense big bang again.
D = d * (t - t0)
The only argument I could see for the need of these terms in addition to just light/ERM would be the ability to detect the existence of something beyond the furthest edges of the universe from where light reaches us through phenomena such as gravitational pull from beyond the edges on the bodies at the edges.
That light is the earliest light we can observe, but it is not the earliest event to have had casual effects on us, nor is the earliest event we can observe.
In particular, that light was emitted about 370,000 years after the Big Bang, while events within the first second after the Big Bang have had casual effects on us.
So there is an important difference between "light" and "casual" in physics.
Unfortunately I’m now just sort of stuck thinking about causality, determinism and free will...not exactly knowing where you are on Earth I guess it’s a possibility you have never been and never will in my light cone, yet my comment was the causality of your reply in some sense. And in maybe an HN 1st you’ve made me reconsider my position, and Recognize I need to more deeply consider causality as having good use outside phenomena from outside light at the edges of space and time and spacetime.
Causality refers to the underlying constraints from the theory (nothing travels faster than the speed of light), this is more general than talking about any particular type of particle/field.
The observable universe is the set of points from which information can reach you. That is not the same as spacetime?