Memory Train

Long time, no blog!

I have moved to a new country.

I am also now visiting the city where I grew up. Memories are surging, and catching up with me at all sorts of times. Today, I will talk at my old college, where I rode emotional roller coasters, up and down the stairs, for three years. Would I recognize myself of ten years ago, if I see him today? Would he consider me just another clueless grownup, who’s lost his way?

Let’s see if I get to cry today. I always believed keeping a straight face was overrated!

The Agnostic Believer

Let me come clean. I am a religious person. That is, if you follow me through a day of my life, you can see things that you may only expect from a devout religious person (at least by Western standards).
However, interestingly, when my partner asked me today if there was a difference between my beliefs and an agnostic person, I couldn’t give her a straight answer.
Don’t get me wrong. I do believe in God. But, at the same time, I cannot tell if God exits or not, as I don’t believe this can be answered (at least in any scientific way). In other words, any statement about the existence of God is not falsifiable, and so can be neither true NOR false. You see, there is a fine balance (if any) between being a believer and a scientist, and now I certainly sound like an agnostic scientist.
But then, how come I act like a religious person? And why do I talk to a god that, by any stretch of my scientific sanity, will never talk back (and even if he does, it’s more likely that I’m going crazy!).
Now, you may think that I must either have multiple personality disorder, or otherwise be a hypocrite (and frankly, it is a struggle).
Being a physicist, I’ve seen my fair share of paradoxes, and know that often the problem is with an implicit assumption in our analysis.
The fact is that life is NOT science. As pleasant and satisfying as falsifiable, scientific facts are, some of the life’s crucial elements, i.e. one’s values or principles, are NOT falsifiable.
While natural scientists have grown accustomed to the concept of absolute true or false, mathematicians know very well that the validity of your theorems depends on the validity of the assumptions/principles that you adopt. There is no true or false assumption, and the only real constraint is the internal consistency of the set of principles that you adopt.
So, there you have it. I can adopt religious values, believe in God, and yet be completely agnostic about his existence.

Now, every human being with a free will needs some sort of values. Otherwise, how would he/she make decisions? And, of course there is no way to logically justify any value, except by basing it upon some more fundamental values. Therefore, one’s set of fundamental values have no logical/scientific/falsifiable justification, and can only be a matter of taste. At this level, the only difference between believers and atheists is that the former (often) choose pre-packaged bundles (with the generic name of god), while the latter are more liberal with their choices (and use the generic name of morality).
Again, at this level, the only real judge is how self-consistent each set of values is. Here, the believers have the disadvantage of inheriting the inconsistencies of their beliefs from their predecessors, which they are often very slow (but eventually willing) to rectify (as religions reform, and sects branch out). However, by the same token, they also inherit the wisdom of centuries of evolution in the religious values, which aim at making these values more and more self-consistent (at a completely practical level). In contrast, although atheists are free in choosing their individual values, they are more likely to face inconsistencies down the road, as they are the first to test drive them (which is the familiar dilemma of Conservatism versus Liberalism).

So, this is why being an atheist is just as illogical and unscientific as being a believer, and why I would prefer some middle ground. Unfortunately, most my colleagues are atheists, and would consider me a crackpot if they knew about my beliefs. But that’s another story, and is why I should remain anonymous ... for now!

Nightly Prayers

The night is not young. No adventures in sight, neither is a bright sunny dawn.
But the words, they are blatant and raw (no audience, no shame).
Thus before you, I stand, naked, rid of any sense, anything that defines me in light.
And I only see you, as we are all alone, in between dusk and dawn, reason and righteous, life and death.
Who else would dare living this purgatory?
There is no way back, but into solitude and despair, into annihilation.
And no way forward, but into illusion, into madness.
Thus before you, I stand, naked, helpless, hopeless, praying for a drop of mercy, a moment in light.
O! My companion of the dark! Will the sky ever open? Will the sun ever rise into such a long lonely night?

The Missing Matter (or the power of cosmic bookkeeping)

It may sound ironic, but one the most significant drivers of new and exciting discoveries in cosmology (or science in general) has been simple (but often boring) accounting.

Trying to think of the best way of explaining why accounting matters in Science, I remembered Feynman’s introduction to “conservation of energy” in the first volume of his celebrated “Lectures of Physics”, which I read a long long time ago. There, Feynman has an intriguing account of how the mother of Dennis the Menace finds ingenious ways of accounting for Dennis’s toy blocks, simply based on that blocks cannot appear from/or disappear into thin air. While this may sound like a trivial statement, its implications can reveal to Dennis’s mother interesting facts about the properties of various systems in Dennis’s room, such as his toy box or bathtub!

One of the most famous examples of the power of bookkeeping was the discovery (or proposal) of neutrinos by Pauli in 1930, to account for the lost energy/momentum in the beta decay of neutrons. In beta decay, a free neutron decays apparently only into a proton and an electron. Since these are both charged particles, they are easy to track in bubble chambers and so their energy and momentum can be measured accurately. However, the sum of the energies and momenta of these particle was not consistent with energy/momentum of a single massive particle (the original neutron), suggesting a breakdown of energy/momentum conservation. Of course, since the energy/momentum conservation is sanctioned by god (part of the ten commandments … check it ;)), Pauli suggested that there must be another neutral particle that carries the rest of the energy/momentum of the original neutron. Sure enough, neutrinos were detected 25 years later, and are now an integral part of the standard model of particle physics.

As it turns out, the job of cosmologists is very similar to that of Dennis’s mother in Feynman’s example. God (like Dennis; no theological overtone intended!) has hidden the matter in various random places in the Universe, and it is our job as cosmologists to account for this missing matter. As Dennis’s mother did, in this process, we will understand interesting properties of our cosmic bathtubs and toy boxes :)

In cosmology, the power of bookkeeping has famously led to the discoveries (or should I say proposals) of dark matter and dark energy. Dark matter has been proposed as a way to account for factors of 10s to 100s mismatch between the gravitational mass (deduced from star/galaxy velocities) and stellar mass of galaxies and galaxy clusters. Dark energy (or cosmological constant, its less exotic predecessor) was first proposed as way to reconcile the mismatch between the flat cosmic geometry (measured via the cosmic microwave background anisotropies) with the cosmic clumpy matter content (as measured in galaxies and clusters). Of course, the situation is not quite as good as the case for neutrinos, as we are yet to detect dark matter or dark energy. While the former is an active industry, most people would bet we’ll never be able to detect dark energy in a non-gravitational way.

Now, I come to the main point of my post, which is a similar discrepancy in accounting, even for the ordinary matter in the Universe. In fact, I decided to write this post (the first scientific post of this blog), after I read Julianne’s nice post on Cosmic Variance about the missing baryons problem, where she explains how we fail to account for most of the baryons (read ordinary matter) in the Universe.
Let me finish by answering three questions about the “Missing Baryon Problem”:
1- How do we know how much ordinary matter there must be in the Universe?
Well, it turns out that Big Bang theory has been very successful in describing the cosmic evolution in the early Universe. This is evidenced by its successful prediction of light element abundances (produced within the first 3 minutes of big bang), as well as the spectrum of anisotropies in the cosmic microwave background. However, Big Bang theory requires 4% of the mass/energy of the Universe to be baryons.
2- So where are most of the cosmic baryons?
As it turns out, we can only see 10-15% of the baryons that the Big Bang theory predicts (see Peebles and Fukugita’s cosmic inventory). The rest is supposedly in a warm-hot intergalactic medium (dubbed WHIM by my colleagues), with very little emission/evidence in any wavelength. However, with advancement of observational technology, we should start to see WHIM’s signature in X-rays or cosmic microwave background, within a decade or so.
3- Is there something wrong with this picture?
Even where we are supposed to see the hot gas, which, as Julianne mentions is in galaxy clusters, there still seems to be some discrepancy, as the baryonic budget is 20-30% less than the big bang prediction (e.g. see here and here). Now, the solution to this may not be as exciting as the last three accounting problems, but I bet it’ll teach us something interesting about our Cosmology.

Introduction

Quite a grim start, eh? But hey, you should start somewhere, and what better place than where you are right now. Let’s start over :)
Hello. It’s me here, trying to tap into the blogosphere for the first time. Now, I have been entertaining the idea of having my own blog for many years (or maybe decades, one may say), but, for different reasons, I couldn’t gather my will to do it until now.
A few words about me:
I am a Scientist by profession, and an Astronomer by training. I make money by doing research in different areas of Astronomy and Cosmology, which often culminate in scientific papers, as well as talks and seminars. I also consider myself a failed poet (!), and this blog is to some extent, an effort to revive my poetic side (although in a different language). I should remain anonymous for now, but I assume that there will be enough information trickling through my posts that will eventually reveal my identity.
A few words about (the idea of) this blog:
Now, as I said before, I am a scientist by profession, and would like a less formal medium to communicate my ideas with my colleagues (if they ever read this blog). However, for more of you, this blog may serve as (a hopefully transparent) window into the world of professional science (in particular Astrophysics and Cosmology), one that you may understand and enjoy at the same time. Nevertheless, for most of you, this will be a reflection of a conflicted individual, one that is caught in between rationality (that is science) and superstition (that is religion), integrity (that is honesty) and hypocrisy (that is politics), and finally, in between fantasy and reality.

Welcome to the world of The Skeptical Cosmologist!

Preface

It builds up civilizations just as it destroys them, drives legions into their dooms, as it brings them back into salvation … What is the name of god?

The man has nothing left, but its humanity. It is the idea of goodness … What is compassion?

When the revenge flows through our hearts, when death and torment loom, it is the panacea, the paradise … What is mercy?

Indeed, this is the universal and the eternal that we seek and are grateful for, as humans, as citizens … and as cosmologists.

Still Standing

This is the story of my life: I was born out of loneliness, lived through despair, and died from isolation.

And I was still standing, dead on skin and in side, with the legions passing by, in fear and awe. “All hail king Solomon”

Thus, of me, Gods were made, worshipped, and burnt.

And I was still standing, senseless, no smile or tears, as dead people are often, and such are gods.

Days go by and nights. Lives forsaken or sought. And yet I am longing for a feeling, for a drop of mortal life. So are heavenly creatures, so empty inside.

And I was still standing, through the storm of life, as mountains do, and so do gods.

What a futile affair! Words struggled so hard.

And I was still standing, mocking their futility ... the story of my life.