The innumerable universes

Mars analemma

There is another you, sitting on an identical Earth, about 10 to the power of 10 to the power of 120 light years away. Other pocket universes will contain entities of almost limitless power and intelligence. If it is allowed by the basic physical laws (which, in this scenario, will be constant across all universes), it must happen. Thus there are unicorns, and thus there are godlike beings. Thus there is a place where your evil twin lives. In an interview I asked Greene if this means there are Narnias out there, Star Trek universes, places where Elvis got a personal trainer and lived to his 90s... Places where every conscious being is in perpetual torment. Heavens and hells. Yes, it does, it seems. And does he find this troubling? ‘Not at all,’ he replied. ‘Exciting. Well, that’s what I say in this universe, at least.’

-- from World Next Door by Michael Hanlon. The Leatherback chapter of my book concludes:

Watching the baby Leatherbacks going like the blazes for the black waters where the majority of them would be eaten by other animals before they grew any bigger than a child’s fist, and where most of the survivors would probably be chewed up in the meat grinder of human civilization, it was nevertheless possible to feel that Schopenhauer’s vision of the world as a place of endless pain and suffering was mistaken. Some small proportion of these young turtles might just survive and return as adults and haul the heavy rock of their own being, now two thousand times as heavy as when they left, once more up the beach. As the stalwart atheist Albert Camus put it, one must imagine Sisyphus happy. And it seemed possible that somewhere, in the innumerable universes, the gods were smiling.

'An earthworm’s brain is more complicated than a lifeless galaxy'

...One cosmic possibility is, roughly, that every possible local world exists. This we can call the All Worlds Hypothesis. Another possibility, which might have obtained, is that nothing ever exists. This we can call the Null Possibility. In each of the remaining possibilities, the number of worlds that exist is between none and all. There are countless of these possibilities, since there are countless combinations of particular possible local worlds...

-- Derek Parfit 
 

Photo: CJ Kale and Nick Selway

Galaxy zoo

Most of the spiral galaxies that decorate our universe have emerged from surprisingly violent pasts, it is reported. They grew their delicate spiral arms after being mashed into a pulp by vast collisions.

Our own spiral galaxy, the Milky Way, is probably one of the few exceptions. It has rotated serenely, undisturbed except by the impact of a few small dwarf galaxies, for about eleven billion years.

It's predicted, however, that Milky Way will collide with the Andromeda Galaxy in about two and half billion years. The resulting 'hyperkinetic smashup' is likely to result in something that looks like this, the colliding Antenna Galaxies:

Little green men

A sustainability solution to the Fermi paradox?

Falling for dolphins

Serge Brunier has a nice photo of the Milky Way. [1]

It is reported that in a collection of stories called Bhagavata purana:

all the visible stars and planets moving through space are likened to a dolphin that swims through the water

Well maybe. It's important not to be sentimental about cetaceans. Dan Everett has a nice story though:

It was about 5:45, the most beautiful time of day, when the sun glows orange and the river’s reflective darkness stands out against the rusty color of sky and the luxuriant spinach green of the jungle. As I sat idly watching and sipping my coffee, I was startled by the sight of two small gray porpoises jumping in synch out of the river. I had no idea that there were freshwater porpoises. Almost immediately, from around the bend came two Pirahã canoes, their riders paddling for all they were worth, in pursuit of the porpoises, trying to touch them with their paddles. It was a game of tag, porpoise tag.

Apparently the porpoises enjoyed themselves because they continually came up just out of reach of the men in canoes. This went on for half an hour, until darkness brought an end to the chase. The Pirahã in the canoes and on the banks (for by now a crowd had gathered) were laughing hysterically. As they stopped chasing the porpoises, the porpoises disappeared. (In all my years watching this contest between mammals, no porpoise has ever been 'tagged').

Everett also writes that:

the most striking thing I remember about seeing the Pirahãs for the first time was how happy everyone seemed.

I assume that when Everett says porpoise he is in fact referring to the Amazon River Dolphin, Inia Geoffrensis.

Footnote

[1] P.S. 22 Sep: A picture of Milky Way centre by Stéphane Guisard.

Brahma days

It may be that all the particles [in the universe] we see were originally collected into a small dense region because it is easier to create a new bubble universe in such a configuration than it is to make a large, dilute universe from scratch. The growth of entropy in our observable universe, and the corresponding arrow of time [without which life -- metabolism, reproduction, evolution, memory -- would not exist], may be a reflection of the larger multiverse's insatiable desire to create ever more entropy by giving birth to new baby universes. If we could just have an angel's-eye view of the entire ensemble, it might all look quite natural.

Or perhaps not...[But] the universe is certainly trying to tell us something; it's our job to attempt to make out what it's saying as best we can.

-- from Our Place in an Unnatural Universe by Sean Carroll, included in What's Next? Dispatches on the Future of Science.

Image: the Antennae galaxies.

Life and gravity

One of 'seven mysteries' of gravity: life on earth 'needs' it. But what is it?

G is the least well-defined of all the constants of nature. It has been pinned down to only 1 part in 10,000, which makes it look pretty rough and ready next to...the Planck constant, which is accurate to 2.5 parts in 100 million...

..."We can make measurements that determine its size, but we have no idea where this value comes from," says John Barrow of the University of Cambridge. "We have never explained any basic constant of nature."

The narrow way

In an attempt to account for what happened before the big bang, as well as the smallness of the cosmological constant, some physicists have been led to a model where our entire observable universe is contained inside a bubble, which is expanding at the speed of light into an exterior space.

But our bubble is not the only one; outside our bubble, there are an infinite number of other bubbles, all expanding just like ours. Sometimes they collide and send waves of death that wash across our universe. In this figure, the regions colored red have already been swept clean by the wave, and the yellow regions can see it coming.

A clear prediction of the model is that Earth resides in the thin sliver, or finger, that forms when two bubbles that have both collided with our bubble narrowly miss one another, indicated here with an arrow. It is thanks to our location here, in a finger, that despite the enormous swaths of our universe decimated by these waves, the odds are exponentially small that they lie in our future. We can all sleep sounder, and it's all because we live in a finger.

-- Alex Dahlen, Princeton University -- The Art of Science, 2009

The longer now

Over the next hundreds of millions of years the sun will continue to get brighter until eventually Earth becomes too hot to inhabit. Previous calculations had pegged that time at about a billion years from now, but the new paper argues that earlier models had neglected the role of atmospheric pressure in regulating the temperature of the planet on astronomical time scales.

Atmospheric pressure is a key variable in the overall greenhouse-gas effect because it determines how much infrared radiation greenhouse gases absorb. Higher pressures mean more absorption and consequently, more heat. Lower pressures have the opposite effect.

Life itself would be the mechanism for these temperature changes. By “fixing” nitrogen, pulling it out of the air and eventually into the Earth’s deep ocean, microbes could be making the atmosphere lighter one atom at a time.

-- Earth 'Gets Billion-Year Life Extension'.

It sounds as if the modeling is inconclusive at this stage. [1]

The claim is that, other things being equal, life-on-Earth will extinguish no more than two billion years from now. [2] Earth-without-life may not, however, vaporise until about 7.6 billion years from now.


Footnote

[1] (added 17 June) see Heavy Weather by Oliver Morton

[2] There are other scenarios. For an overview see How will the Biosphere End? in Big Questions Questions in Ecology and Evolution by Thomas Sherratt and David Wilkinson. There is said to be a 50% chance of a collision with the asteroid Eros in the next 100 million years. This would not produce enough energy to vaporise the oceans but it would release an order of magnitude more energy than the impact thought to have ended the Cretaceous. Not necessarily an end to all life, but perhaps an end to the multicellular kind.

Images: Home, Yann Arthus-Bertrand

Lazarus

This interview with Ray Kurzweil (whose Age of Spirital Machines I reviewed in '99) is fascinating. So much seems credible. [1] Then I get to the last paragraph and wonder, is he insane or joking in some way? Or am I missing something?


Another story imagines eternal life beginning not in 2045 or so, but at 'the Omega point' far in the future of the universe. As Marcus Chown introduces the idea:

You've had a long life but, finally, your time has come. If you were a wit like Oscar Wilde, you would say something amusing like: 'Either these curtains go or I do'. But you are suffused by such an awful tiredness that you can barely think, let alone speak...You draw one last breath...

...and it is summer and you are young again. Your favourite dog -- the one that loved you so much as a child and thought you would never see again -- has knocked you to the ground and is licking your face furiously. Through tears of joy, you see your father and mother -- long dead -- standing over you. They are young -- just as they were when you were ten years old -- and they are laughing and stretching out their hands to you.

Footnote

[1] (Added 13 May): See, e.g., Will designer brains divide humanity?

The never ending days of being dead

The Cat's Eye Nebula, which may be something like what the sun will look like when it dies.

'Older', and 'everywhere'

• Traces of [multicellular] animal life have been found in rocks dating back 635 million years.

• research claims there are at least 361 intelligent civilisations in our galaxy and possibly as many as 38,000. [1]

(See also Just wondering)

Footnote

[1] 15 Feb: Galaxy has 'billions of Earths'.

The Now

Once Einstein said that the problem of the Now worried him seriously. He explained that the experience of the Now means something special for man, something essentially different from the past and the future, but that this important difference does not and cannot occur within physics. That this experience cannot be grasped by science seemed to him a matter of painful but inevitable resignation. I remarked that all that occurs objectively can be described in physics; and, on the other hand, the peculiarities of mans’ experiences with respect to time, including his different attitude towards past, present and future, can be described and (in principle) explained in psychology.

But Einstein thought that these scientific descriptions cannot satisfy our human needs: that there is something essential about the Now which is just outside the realm of science.

-- Rudolf Carnap, quoted by Lee Smolin in On the reality of time and the evolution of laws (PIRSA:08100049)

Right now we are both alive. Better you and I not think too much about this fact, or we might be overwhelmed and paralyzed by joy.

-- Roberto Unger

[Image: a comb jelly, in vague allusion to the Meduso anthropic principle although, of course, comb jellies and jellyfish are not the same]

Bounded in a nutshell

A previous post on this blog, Kin, noted five characteristics or behaviours that are still regarded as uniquely human, and I've suggested (as have others) another: the capacity to do science itself. Here is David Deutsch in The Fabric of Reality:

Many other physical systems, such as animals' brains, computer or other machines, can assimilate facts and act upon them. But at present we know nothing that is capable of understanding an explanation -- or of wanting one in the first place -- other than the human mind.

And in What is our place in the cosmos? Deutsch takes this all the way:

one physical system, the [human] brain, contains an accurate working model of the other, the quasar; not just a superficial image of it – though it contains that as well – but an explanatory model, embodying the same mathematical relationships and same causal structure – that is knowledge. And if that wasn't amazing enough the faifthfulness with which the one structure resembles the other is increasing with time. That is the growth of knowledge. So the laws of physics have this special property: the physical structures as unlike each other as they can possibly be can embody the same mathematical and causal structure and do it more and more so over time. ..We are a 'chemical scum' [1] that is different. This chemical scum contains with ever increasing precision the structure of everything. [2]

Footnotes

1. Stephen Hawking’s (jokey) description of humanity: "The human race is just a chemical scum on a moderate size planet, orbiting around a very average star in the outer suburb of one among a hundred billion galaxies."

2. In The Fabric of Reality, Deutsch argues that "we are not heading away from a state in which one person could understand everything that is understood, but towards it".

Images: A Five Quasar Gravitational Lens, Heart and soul nebulae

Life tuned differently

"You have no idea what life would be like in a universe with different constants," [says Fred Adams]...[He] reckons his results, which will be published in the Journal of Cosmology and Astroparticle Physics, suggest that the "specialness" of our universe could well be an illusion. And this is only the very beginning of what can be probed to undermine the idea that our universe is fine-tuned for life. There are plenty more constants and processes that can be tinkered with, he says.

-- from In the multiverse, stars burn black, a report on work that indicates that very different life forms to the ones we know might be better suited to some other universes in which the range of possible values for three constants involved in the formation of stars are different.

A cosmic Cheshire cat

In the story, Alexander asks one of the wise men, "which animal is the most cunning?". The Brahmin answers, "the one Man does not yet know."

So it goes for the Higgs Boson, which physicists hope to add to the elementary particle menagerie.

[Higgs himself is famously not happy with the name. I would vote for 'Boojum' had it not already been used to describe something else. But the term is now fixed.]

In the 'Cerncast' accompanying the Guardian package of articles about the LHC, Jim al-Khalili suggests that sometimes it's what you don't find what you're expecting that life gets most interesting. So, for example, the failure by Michelson and Morley to measure movement of the Earth against a luminiferous aether help prepare the way for the theory of relativity. It would be equally momentous, said al-Khalili, if the LHC finds no Higgs Boson [see also article here].

If it turns out not to be there (and at present this is considered unlikely), then perhaps this non-existent particle could be called, or not be called, the 'Grin' -- standing for 'gradually receding into nothing' -- of a cosmic Cheshire cat.

The executioner's argument was, that you couldn't cut off a head unless there was a body to cut it off from: that he had never had to do such a thing before, and he wasn't going to begin at his time of life. -- Alice

Whereof can one not speak

Why should we not talk about an 'extraterrestrial brother'?, asks Jose Gabriel Funes. Why not indeed...if one is there? But let's start by taking a cappuccino with Guy Consolmagno.

Image: a planetary nebula called Abell 39