Big

The Copernican principle states that, on the large scale, the universe is homogenous and is nowhere special.  But it is reported that at least three phenomena call that into question:

A void almost 2 billion light years wide called the CMB coldspot. 

A structure strung out over 4 billion light years containing 73 quasars known as the Huge Large Quasar Group. 

A group of gamma-ray burst emitting galaxies that form a ring 5.6 billion light years across – 6% of the size of the entire visible universe.

Some physicists argue that these phenomena may be evidence for brane theory — the idea that what we perceive as our universe is a single four dimensional membrane floating in a sea of similar (mem)branes spanning multiple extra dimensions.

Image via Daily Galaxy

Randomly different initial conditions

Modern cosmology involves the idea of quantum genesis — tracing back the cosmic expansion to an origin in a singularity where the space that now contains 100 billion galaxies was smaller than an atom. The inflationary scenario is an adjustment of standard big bang to include an extremely early phase of exponential expansion. The idea was developed to explain why the universe now is very smooth and geometrically flat. Inflation has tentative support from the nature of small temperature variations in cosmic background radiation. If inflation is correct, the universe began as quantum fluctuation. The precursor state would have been an ensemble of quantum fluctuations, perhaps infinite in number, each with randomly different initial conditions. Some of them inflated into large space-times like our own. Others were still born. This process can be timeless and eternal.

Beyond: Our Future in Space by Chris Impey (2015)

Mass ends in B flat

In 2003, [astronomers] discovered the longest, oldest, lowest note in the universe — a black hole’s song... Although it is too low and deep for humans to hear, the B flat note, 57 octaves below middle C, appeared as sound waves that moved out from explosive events at the edge of a supermassive black hole in the galaxy NGC 1275. 

The notes stayed in the galaxy and never reached us, but we couldn’t have heard them anyway. The lowest note the human ear can detect has an oscillation period of one-twentieth of a second. This B flat’s period was 10 million years.

Joanna Klein An Earthling's guide to black holes

Supermassive black holes — a million to a billion times more massive than our sun — exist only in the center of a galaxy. At the center of the Milky Way, 26,000 light-years from Earth, scientists are hoping to make an image of Sagittarius A*, which is believed to be our own supermassive black hole, with the mass of four million suns.

Image from Utriusque Cosmi by Robert Fludd (1622)

'We have just awakened into this cosmos, as from a dream'

The ancient cosmos was not a complex mathematical structure. It was a sensory world, stitched together from people’s everyday experiences, people who had never seen Earth’s curves from orbit, or the night sky as magnified by a telescope...In the sacred Sanskrit text the Rig Veda, the universe begins as a symmetrical orb of pure potential, an egg surrounded by an infinite amniotic sea, which splits into two bowls of earth and sky, with the yolk-like sun hovering somewhere in the middle. 

The earth that emerged from this primordial separation was usually a flat, round disc, wrinkled by mountains, cut through with rivers, and surrounded by ocean on every side. Above this disc was the closed dome of the sky, and below it was an underground realm of equivalent size. Together, they formed a sphere. Every night, the sun would travel through the invisible underworld after teetering over the horizon’s edge. The ancients knew this because the sun reappeared at dawn on the earth’s opposite side.

from Is Cosmology Having a Creative Crisis? by Ross Anderson

Images: Nebra Sky Disk, mid second millennium BC (Rainer Zenz) and illustration from Thomas Wright's Original Theory or New Hypothesis of the Universe (1750), an influence on Immanuel Kant's Universal Natural History and Theory of Heaven (1755)

Signposts

At a talk for non-specialists on 21 February, David Tong outlined three big problems in physics [1], which I oversimplify/misrepresent as follows:

Dark energy.  We've known for nearly a hundred years that the universe is expanding. It as if there is an antigravity force causing everything to repel everything else. We have no idea what it is. It’s 70% of the energy of the universe, it’s increasing all the time and we don’t understand it. Our best calculations are wrong by a factor of 10⁶⁰ .

Black holes.  Information that goes into a black hole is lost forever. It does not reappear in Hawking radiation. But this cannot be.

Holography. It may be that our three dimensional world is actually a mirage. The correct description will be one in which the laws of physics are written on a two dimensional surface, and the laws of physics we can see in the universe are encoded on this surface in the same way that a hologram encodes a three dimensional surface.

So, Tong concluded, there is a lot in the fundamental physics that we simply don’t understand, and that it seems unlikely we’re going to get guidance from experiment. Looking to history, however, it is precisely when there is a crisis that physics has thrived. He is optimistic about progress.


Note [1]: Some people say there are three great mysteries in science as a whole: the origin of the universe, the origin of life and the origin of consciousness.

Image: Douglas Griffin

The two-headed-cow question

Instead of looking at all of space-time, [Raphael Bousso] homes in on a finite patch of the multiverse called a “causal diamond,” representing the largest swath accessible to a single observer traveling from the beginning of time to the end of time. The finite boundaries of a causal diamond are formed by the intersection of two cones of light, like the dispersing rays from a pair of flashlights pointed toward each other in the dark. One cone points outward from the moment matter was created after a Big Bang — the earliest conceivable birth of an observer — and the other aims backward from the farthest reach of our future horizon, the moment when the causal diamond becomes an empty, timeless void and the observer can no longer access information linking cause to effect.

from The Multiverse's Measure Problem by Natalie Wolchover and Peter Byrne

"Consciousness takes place in time"

The problem of consciousness is an aspect of the question of what the world really is. We don’t know what a rock is, or an atom, or an electron. We can only observe how they interact with other things and thereby describe their relational properties... 

While [the future of science] is unpredictable…the only certainty is that we will know more in future. For on every scale, from an atom’s quantum state to the cosmos, and at every level of complexity, from a photon made in the early universe and winging its way towards us to human personalities and societies, the key is time and the future is open.

from Time Reborn by Lee Smolin (2013)

Image: The White Fence by Paul Strand (c1917) via wikipedia

Darkness invisible

The tenth cosmic myth, according to Marcus Chown [1], is that the stuff that science has been studying for 350 years is the important stuff.  Because only 4.9% of the universe is made of atoms:

About six times as much - that is, 26.8 per cent - is invisible, or "dark" matter [which] reveals itself by tugging with its gravity on the visible stars and galaxies.  No one knows what the dark matter is made of, though speculation ranges from hitherto undiscovered subatomic particles to fridge-sized black holes the mass of Jupiter.

But even the dark matter is trumped by the final component of the universe. About 68.3 per cent is dark energy. It is invisible, it fills all of space and it has repulsive gravity [which] is speeding up the expansion of the universe...

What all this tell us is that the stuff science has been studying for the past 350 years is not the most important stuff. In fact it is but a minor component of the universe...

But proportion is not necessarily the same as importance. Iron, for example, constitutes just 0.00067 per cent of the elemental composition of the human body yet it is essential to life.  Further, the existence of dark matter and dark energy are still disputed. All the same, Chown's point is worth attention. [2] As Paul Broks put it:

We may, as a species, be suffering the cosmic equivalent of Anton’s syndrome, the neurological condition in which patients rendered totally blind by damage to the visual cortex believe they can see perfectly well. 

Sometimes, an overlooked absence contains clues to something amazing.  In 1814 Joseph Fraunhofer discovered that the apparent continuity of a rainbow is an illusion:

There are tiny gaps, dim or black arcs of missing colors, too narrow for us to see in the glare of natural rainbows...Fraunhofer eventually cataloged 576 of these gaps, or "absorption lines"...Today tens of thousands are known. [3]

Analysis of the "gaps" in the light from stars has taught us what they are made of, and that star-stuff is the same as Earth-stuff.



Image: the Trifid nebula, or nothing very much at all really, by R. Jay GaBany via Cosmotography

Notes:

[1]  Autumn 2014 edition of New Humanist on the occasion of the publication of the paperback of What a Wonderful World

[2] "Our worldview has at times been trapped in a rut because some of the most important clues are buried in the details of what we see around us." Caleb Scharf, The Copernicus Complex (2014).
[3] Longing for the Harmonies, Frank Wilczek and Betsy Devine (1987)