March 29, 2025
 

I must say, I'm far from being the one who can best express its meaning, not even close. Still, I must warn you that I am not the first, and certainly won’t be the last, to write about the pale blue dot. Since Carl Sagan gifted us with this reflection, countless thinkers, scientists, and astronomy enthusiasts have revisited this iconic image to ponder our place in the universe.

At a distance of about 6 billion km, a camera aboard Voyager 1 captured one of the most iconic images in the history of science. Amid the vastness of space, a small bluish speck 'stands out' against the dark expanse. That tiny, almost imperceptible dot is our planet, Earth. At that moment, Voyager 1, already on its journey beyond the Solar System, recorded the fragility and uniqueness of our home in the cosmos.

The image, now known as the Pale Blue Dot, has become a symbol of our existence, a visual testament that, despite the complexity of life on Earth, we are merely a minuscule fragment in the infinite ocean of the universe. Carl Sagan, a renowned astronomer and science communicator, deeply reflected on this photograph, transforming it into a powerful reminder of both our insignificance and our responsibility. Insignificance and responsibility... it may seem contradictory, but it isn’t. Feeling insignificant in the face of such vastness does not erase the responsibility we bear for our actions. On the contrary, it may even reinforce it.

In his book Pale Blue Dot, Sagan immortalized his reflections on this distant view of Earth. He invites us to reconsider our position in the cosmos:

"Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there--on a mote of dust suspended in a sunbeam." 

He reminds us that every human being who has ever existed inhabited this tiny dot – kings and peasants, saints and sinners, heroes and villains, inventors and explorers. Wars were fought, empires were built and crumbled, dreams were dreamed and forgotten, all within the confines of this small world, floating in the void.

Sagan’s reflection also extends to the absurdity of our conflicts. How many rivers of blood have been spilled by generals and emperors in the illusion of conquering a fraction of this minuscule dot? How many times have human beings killed and massacred their fellow humans over insignificant differences? In our blindness, we forget that we all share the same fate, bound to the fragility of this pale blue dot.

Our illusion of grandeur crumbles before the cosmic reality. To the universe, we are nothing more than a tiny speck of dust illuminated by the sun. The belief that we occupy a privileged position dissolves when we realize that, beyond this small refuge, there are no signs of help, no rescue coming from the stars to save us from ourselves. We occupy not a central throne, but an intriguing, unremarkable corner of the cosmos, suspended in a sunbeam, left to our own devices.

For now, Earth is the only home we know. No matter how much we dream of colonies on other planets, no matter how advanced our technology becomes, there is still no other place where we can live and thrive. We may visit other worlds, but we cannot yet inhabit them. We are confined to this lonely point in space, and here, we must learn to coexist.

Given this reality, the only sensible choice is to care for our home, to protect the only refuge we have. Our survival does not depend on territorial conquests or relentless expansion but on our ability to preserve the planet and live in harmony.

The distant vision captured by Voyager 1 reminds us that, in the end, we are all in this together, sailing through an indifferent cosmos. Perhaps that is the greatest lesson of the Pale Blue Dot: that we need each other and that Earth, though small and solitary, is the most precious place we have ever known.

If we can truly understand this, perhaps we can become worthy of this tiny home in the infinite.

That’s all, folks!

Hasta la vista.

December 17, 2024
 

Dear Faculty and Students of the Center for Extension and Research in Water and Effluents (CEPAE) at the Federal University of São Carlos (UFSCar), Lagoa do Sino Campus,  

As another year comes to an end, I would like to take a moment to reflect on everything we have experienced and achieved. As the coordinator of CEPAE - alongside my colleague Beatriz Gonzalez - I have the privilege of witnessing the growth and dedication of our students, who come from the Biological Sciences, Administration, Agronomic Engineering, and, in greater numbers, Environmental Engineering programs.  

This has been a year full of challenges. An intense year, often stressful, but also filled with learning. We have overcome obstacles, adapted to new realities, and, with commitment, always strived to offer the best in teaching, research, and extension. Numerous partnerships were established, each one enriching our academic and professional journey. We have made progress and provided experiences and opportunities for the development of everyone involved in CEPAE.  

It is important to emphasize that, although the technical cause that unites us is essential -- and the technical aspect itself holds great importance --we must never lose sight of the social dimension of our work. The impact we generate in society -- however small in the face of the world's vast challenges -- is what gives meaning to every action, every research project, and every initiative. It is through collective work and joint effort that we can transform technical knowledge into real and effective solutions for the challenges we face.  

It is also worth remembering that our group is still in its early years, just over a year and a half old. While we have accomplished a lot, we know that we still have a long journey ahead, with many lessons yet to be learned. But it is precisely in this continuous process of growth that we find our strength, and every step forward is a significant advancement for CEPAE and UFSCar as a whole.  

Finally, I would like to highlight a crucial point for the future of our work: universities need to break out of their ivory towers, step beyond the walls that often confine them, and engage with society, bringing the knowledge produced in classrooms and laboratories to the service of communities (especially the most vulnerable ones) and real-world challenges. Interaction with the outside world, with people and local realities, is essential for our mission in teaching, research, and extension to be fully and effectively realized. However, it is equally important to recognize that knowledge is not the exclusive domain of universities. Communities also have much to teach us, with their practices, traditional knowledge, and unique ways of understanding the world, which are just as valuable and fundamental for building fairer and more sustainable solutions. This exchange of knowledge should be seen as a two-way street, where both sides learn, grow, and transform.  

I wish everyone a well-deserved period of rest so that we can return next year with renewed energy, ready to face new challenges, learn, and achieve even more.  

And so, another trip around the Sun is completed, bringing with it renewed hope, strength, and dedication. May 2025 bring us more partnerships, more learning, more collective work, and, above all, more progress.  

That's all, folks!  

Hasta la vista.

May 2, 2024
 

I want to share with you the latest opinion article published on the Amazon portal "Brasil Norte Comunicação." This article, titled "Reflections on Environmental Racism in Brazil," is the result of a collaboration between myself and biologists André Pereira and Débora Souza.

In the current context, it is crucial to expand dialogue and raise awareness about the various forms of injustice and inequality that permeate our society. Environmental racism is one of these pressing issues that demands our attention and collective action.

In our article, we discuss how environmental racism disproportionately affects marginalized communities, often relegated to degraded areas and exposed to harmful environmental conditions. Furthermore, we highlight the neglect and lack of investment in basic sanitation infrastructure, an element that contributes to the perpetuation of these inequalities.

With that said, we invite you to read our full article on the "Brasil Norte Comunicação" portal and to join us in this important conversation.

Link to the article: https://bncamazonas.com.br/reflexoes-sobre-o-racismo-ambiental-no-brasil/  

That's all, folks!
Hasta la vista.

April 06, 2024

In the contemporary world, while many of us enjoy the luxury of potable water with a simple turn of the tap, 1.2 billion human beings are deprived of this basic right. Despite being a vital element for human existence, water remains out of reach for a significant portion of the global population. Even more alarming is that it’s not just the lack of access to clean drinking water, but also the absence of proper environmental sanitation systems in general, including stormwater management, solid waste disposal, and air pollution control, all within the growing context of climate change. This grim reality represents not only a public health and environmental crisis but also a humanitarian one — a true disaster.

The scale of the problem is: GLOBAL. From southern Argentina to India; from Russia to the Middle East; from São Paulo to Southeast Asia.

In addressing these urgent issues, we not only focus our minds and efforts on the health and well-being of the most vulnerable communities, but we also promote a sustainable future for our planet. Clean water and proper sanitation are not luxuries — they are fundamental human rights that must be guaranteed to all, regardless of geographic location or socioeconomic status.

Within this context, CEPAE, acknowledging its limitations, focuses on the following Sustainable Development Goals (SDGs): Good health and well-being (SDG 3); Clean water and sanitation (SDG 6); Reduced inequalities (SDG 10); Sustainable cities and communities (SDG 11); Climate Action (SDG 6); Life below water (SDG 14).

Now, considering our limitations... It’s easy to feel overwhelmed by the magnitude of the problems we face today, right? Climate change, social inequality, environmental degradation — the list goes on. Sometimes, it may seem like our efforts are insignificant in the face of these monumental challenges. But perhaps that’s exactly where the misconception lies.

While we may not have the power to solve all the world’s problems, every action we take toward a better world matters. Every conscious choice we make, every small gesture that supports, every voice raised in defense of justice — all of these contribute to a larger whole.

So, let’s pose a new question that’s implicit here: "Are we going to save the world?" Of course not, not even close! I’m no one special, and I’m perfectly fine with that. (Honestly, we can’t even save ourselves...) I fully embrace my insignificance without shame, and yet, I still believe I can make a difference. It may sound contradictory, but it’s not. Yes, we can make a difference in some way. We can inspire others, influence policies, and contribute to promoting change. We can build a more just, more sustainable, and more hopeful future.

One step at a time.

It’s that, or complete barbarism.

So, this is how CEPAE begins… A small group of people coming together to use science and technology to aid the most vulnerable, striving to find solutions that promote equal access to technologies that are predominantly controlled by large capital interests. We aim to use creativity to develop low-cost technological alternatives to provide for the most basic human needs — needs that are largely monopolized by major financial conglomerates. I don’t underestimate the power of small actions and small things — because they do matter!

That's all, folks!
Hasta la vista.

I love fluid mechanics. And although I don’t consider myself a true expert on the subject, I’ve been dealing with these issues a little more deeply since my engineering college days, throughout my professional life as an engineer, professor, and consultant. I’m curious, and that curiosity drives me—it’s enough for me. So, in my explorations of fluid mechanics, especially in the study of open channel flow, one question has always intrigued me: how to accurately determine the roughness coefficient related to the walls and bottom of channels?

I've heard highly qualified colleagues respond with: "Give up! That doesn't exist! We know nothing about turbulence!" Haha!

That open-channel running through your city was designed to transport fluid (almost always water) and is directly subject to atmospheric pressure — by the way, I hope it wasn’t just thrown in there without careful planning and criteria.

This topic has been the subject of many debates I’ve had the chance to participate in with truly knowledgeable people. The famous Manning roughness coefficient has always sparked conflicting emotions among those involved, myself included (learning far more than teaching). It’s been the cause of laughter and mockery, fascination, furious attacks at conferences, and passionate defenses in the halls of universities. This century-old symbol of hydraulic engineering continues to haunt my thoughts because, honestly, I feel like a child playing by the seashore — that child who feels incapable of diving into the depths of the issue with the rigor it deserves. As Isaac Newton would say, the ocean of truth is vast and — until some crazy folks come along to clarify it — still mysterious!

Here’s a bit of historical context. Brilliant engineers like Frenchman Henri-Émile Bazin and Irishman Robert Manning introduced various formulas in the context of computing hydraulic parameters for channels. However, all made the simplifying assumption that the flow is steady, uniform — and that there is no variation in the fluid's density along the way, meaning the flow is incompressible. Essentially, these formulas take into account average velocity, hydraulic radius, energy slope, and the roughness coefficient (!). And, essentially, that’s how we still design channels today (!). The physics are there, we just can’t fully see their complexity and beauty. Because that’s what we are: merely children lost in a dark room or playing by the seashore.

A note about average velocity: a simplification, especially under turbulent conditions, where particle trajectories are not parallel, constantly changing direction and becoming irregular. Turbulence is an unpredictable madness in experimental terms and highly sensitive to initial conditions.

A note about the energy slope: the result of the sum of potential, pressure, and kinetic energy, built upon Bernoulli’s Principle, which was deduced from simplifying assumptions in an ideal scenario.

But that’s not the point here. Let’s return to roughness.

Continuing... The Manning formula was developed from seven different formulas, which were themselves based on Bazin’s experimental data and later verified by over 200 observations. Ok, there’s a good estimate. Due to its simplicity and satisfactory results for practical applications, Manning’s formula became the most widely used for calculating steady and uniform flow in channels.

When applying Manning’s formula, the biggest challenge lies in the accurate use of the roughness coefficient n (there it is again!); for which there is no precise method of determination (again?). At this point in our knowledge, selecting a value for n essentially means estimating the flow resistance in a given channel, which is indeed a matter of intangibles. For veteran engineers, this means a “sound” judgment for good engineering practice; for beginners, it may be no more than a well-informed guess (at best), and different individuals will arrive at different results.

To guide the proper determination of the roughness coefficient, the legendary Professor Ven Te Chow proposed four general approaches, namely:

• Understand the factors that affect the value of n and, thus, acquire a basic knowledge of the problem to narrow down the wide range of assumptions;

• Consult a table of typical n values for different types of channels;

• Examine and familiarize yourself with the appearance of some typical channels whose roughness coefficients are known;

• Determine the value of n by an analytical procedure based on the theoretical velocity distribution in the cross-section of the channel and measured data on velocity or roughness.

Ok, Professor, these are excellent tips, and we’ve done safe projects following your advice, but they still help us to estimate and only estimate — they help us reach, at most, an approximate judgment.

It’s not uncommon for engineers to think of a channel as having a single n value for all occasions. In reality, the value of n is highly variable and depends on several factors. In selecting a suitable value of n for various design conditions, a basic knowledge of these factors is very useful. The factors that most influence the roughness coefficient in both natural and artificial channels will be described in another post. It should be noted that these factors are somewhat interdependent; hence, the discussion of one factor may be repeated concerning another.

The intense battle has been ongoing since the 19th century, when various mathematical propositions emerged in an attempt to reduce the uncertainties surrounding this coefficient — however, even today, I consider it impossible to predict with accuracy the magnitude of abrasive phenomena and foreign matter entering the channel, for instance. This involves so many variables that our frustration truly increases. But what is a hydraulic engineer if not someone who, in the vast majority of cases, relies on experimental data and coefficient adjustment to solve problems?