Thursday, October 14, 2021

How Big Is the Universe? Don't You Ever Wonder?

 

I saw no Way — The Heavens were stitched

By Emily Dickenson (1830 – 1886)

I saw no Way — The Heavens were stitched —
I felt the Columns close —
The Earth reversed her Hemispheres —
I touched the Universe —

And back it slid — and I alone —
A Speck upon a Ball —
Went out upon Circumference —
Beyond the Dip of Bell —

If your brain is mathematically challenged and you struggle understanding the science of physics like me, comprehending the scale of the universe is next to impossible. Yet, contemplating the size of the cosmos is an irresistible challenge to even simple minds like mine.

Size and Light

So, let's examine the vast universe together. Here is an explanation of the size of the universe by Dr. Luke Davies, an ARC Future Fellow at the International Centre for Radio Astronomy Research. He uses light to make things clearer …

In the time it took you to read this far, a photon of light leaving the Sun has travelled about 10 million kilometres – equivalent to travelling around the Earth 250 times.

Light that leaves our second nearest star, Proxima Centauri, takes just over four years to reach Earth and so we can define it as four light years away.

As such, if you were to look at Proxima Centauri, you would not be seeing the star as it is right now, but how it 'was' 4 years ago!

We see all things in the universe as they were in the past, whether they're on the other side of the room or the other side of the galaxy.

To take this concept further, the nearest large galaxy to us is Andromeda which is so big and close that you can see it in the night sky with your naked eye.

What you're really seeing is 1,000's of billions of stars in a configuration similar to our Milky Way. However, all of those stars are about 2.5 million light years away, which means you're seeing Andromeda as it was 2.5 million years ago.

(Dr. Luke Davies. “How big is the universe?” https://phys.org/news/2015-10-big-universe.html. phys.org. Sciencenetwork Wa. October 05, 2021.)

And, Davies explains that the entire universe is littered with galaxies just like the Milky Way and Andromeda, and using our most powerful telescopes we can see light from galaxies that has taken more than 13 billion years to reach us.

Since a photon of light left one of these galaxies, life sparked into existence and evolved. Dinosaurs ruled the Earth. Humans appeared, developed tools, art, science and technology, built the Hubble Space Telescope, put it into orbit and finally stopped that poor photon on its 13 billion year journey!

The universe is about 13.8 billion years old, so any light we see has to have been travelling for 13.8 billion years or less – we call this the 'observable universe'.

However, the distance to the edge of the observable universe is about 46 billion light years because the universe is expanding all of the time.

Imagine that a photon of light is emitted from a point on the edge of our observable universe.

While that photon has been traveling through space, the universe has expanded. We have moved away from the point where the light was emitted, and it has moved away from us!

Though the light might have only traveled for 13.8 billion years, the distance from us to the point it came from is, at present, 46 billion light years!”

(Dr. Luke Davies. “How big is the universe?” https://phys.org/news/2015-10-big-universe.html. phys.org. Sciencenetwork Wa. October 05, 2021.) 


The Hubble Deep Field series (scientists made two more such observations) offered a kind of core sample of the universe going back nearly to the Big Bang. That vast amount of space includes anywhere from 200 billion to 2 trillion galaxies, according to varying estimates. And each galaxy has, on average, around a 100 billions stars.

In 2016, a study published in The Astrophysical Journal by a team led by the University of Nottingham’s Christopher Conselice used a mathematical model of the early universe to estimate how many of those as-yet-unseen galaxies are lurking just beyond Hubble’s sight. Added to existing Hubble observations, their results suggested such galaxies make up 90 percent of the total, leading to a new estimate—that there may be up to two trillion galaxies in the universe.

Such estimates, however, are a moving target. As more observations roll in, scientists can get a better handle on the variables at play and increase the accuracy of their estimates.

(Jason Dorrier. “Universe? A New Answer From the Darkest Sky Ever Observed.” SingularityHub. January 15, 2021.)

Billions of years, two trillion galaxies, expanding universe – my head is spinning trying to figure the size and distance. So how big is our universe? The truth is we don't really know, but it's big. And it's still getting bigger all of the time. That much scientists say they “know.”

Scale 

I still need help if I want to understand the vast cosmos. How about the size of “things” in the universe? Perhaps knowing the range of mass or volume of stars and the like will help alleviate my consternation.

In his book, The Zoomable Universe (2017), Caleb Scharf takes us on an epic tour that starts from the ends of the observable universe, exploring its biggest structures, like groups of galaxies, and goes all the way down to the Planck length – less than a billionth of a billionth of a billionth of a meter: the scale at which classical ideas about gravity and space-time cease to be valid and quantum effects dominate. This is the “quantum of length,” the smallest measurement of length with any meaning.

Scharf is the director of Columbia University’s Astrobiology Center and author of the 2012 book Gravity’s Engines: How Bubble-Blowing Black Holes Rule Galaxies, Stars, and Life in the Universe.

Scharf's The Zoomable Universe explores scale – something we all have direct experience of, even intuitively. Maybe he can help us understand the weirdness and vastness of the universe. He explains …

Scale is fascinating. Scientifically it’s a fundamental property of reality. We don’t even think about it. We talk about space and time – and perhaps we puzzle more over the nature of time than we do over the nature of scale or space – but it’s equally mysterious.

We learn to evaluate the size of things. But we’re operating as humans in a very, very narrow slice of what is out there. And we’re aware of a very narrow range of scales: In some sense, we know more about the very large than we do about the very small.

We know about atoms, kind of, but if you go smaller, it gets more uncertain – not just because of intrinsic uncertainty, but the completeness of our physics gets worse. We don’t really know what’s happening here. That leads you to a mystery at the Planck scale. On the big scale, it’s stuff we can actually see, we can actually chart.”

(Dan Garisto. “This Will Help You Grasp the Sizes of Things in the Universe.” Nautilus. November 08, 2017.)

Scharf says there are quarks – subatomic particles and fundamental constituents of matter – and then there’s 20 orders of magnitude smaller but on the larger scale there’s some of that too … the emptiness of interstellar space. It is striking how empty most of everything is on the big scale and the small scale. According to Scharf, all the Milky Way’s stars can fit inside the volume of our solar system.

We have all this rich stuff going on in the scale of the solar system and the earth and our biological scale. That’s where we’ve gained the most insight, accumulated the most knowledge. It is the scale where matter seems to condense down, where things appear solid, when in fact, it’s equally empty on the inside.

But is that a human cultural bias? Or is that telling us something profound about the nature of the universe? I don’t really know the answer to that. But there’s something about the way we’re built, the way we think about the world. We’re clearly not attuned to that emptiness.”

(Dan Garisto. “This Will Help You Grasp the Sizes of Things in the Universe.” Nautilus. November 08, 2017.)

 

An Infinite Or Finite Universe?

So, the universe is very big and very small … and very, very empty. Still having trouble with scale? Me too. Maybe the damn thing is infinite – boundless or endless. Science tells us nothing can be “infinite,” since in order for something to "be,” it must be defined and measurable. If it isn't, then the object would exist in a perpetual state of creation and couldn't be said to "be" anything at all … yet.

Still, even if infinite is an imaginary concept that the mind has created, we are trying to understand size. Let's see what science says about the concept of boundless in an ever-expanding universe.

The ancient Greeks recognized that it was difficult to imagine what an infinite universe might look like. But they also wondered that if the universe were finite, and you stuck out your hand at the edge, where would your hand go? The Greeks' two problems with the universe represented a paradox - the universe had to be either finite or infinite, and both alternatives presented problems.

To measure the universe, astronomers look at its curvature. These scientists speculate that if the universe is perfectly geometrically flat, then it can be infinite. However, if it's curved, like Earth's surface, then it has finite volume.

So which shape really is it? Nobel Prize-winning cosmologist John Mather of NASA’s Goddard Space Flight Center, also the chief scientist for the James Webb Space Telescope, maintains that recent observations of cosmic microwave background radiation (CMB) remaining from the time of the Big Bang support the idea of the universe being flat, without any curvature (at least to the limit of what is observable).

You might think this means the universe is infinite. But even if the universe is finite, it doesn't necessarily mean there is an edge or an outside. It could be that our three-dimensional universe is embedded in some larger, multidimensional construct.

Multidimensional construct? Paul M. Sutter, an astrophysicist at SUNY Stony Brook and the Flatiron Institute in New York City looks at the perspective this way …

When you imagine the universe, you might think of a giant ball that's filled with stars, galaxies and all sorts of interesting astrophysical objects. You may imagine how it looks from the outside, like an astronaut views the globe of the Earth from a serene orbit above.

But the universe doesn't need that outside perspective in order to exist. The universe simply is. It is entirely mathematically self-consistent to define a three-dimensional universe without requiring an outside to that universe. When you imagine the universe as a ball floating in the middle of nothing, you're playing a mental trick on yourself that the mathematics does not require.

Granted, it sounds impossible for there to be a finite universe that has nothing outside it. And not even "nothing" in the sense of an empty void – completely and totally mathematically undefined. In fact, asking "What's outside the universe?" is like asking "What sound does the color purple make?" It's a nonsense question, because you're trying to combine two unrelated concepts.

It could very well be that our universe does indeed have an "outside." But again, this doesn"t have to be the case. There's nothing in mathematics that describes the universe that demands an outside.”

    (Paul Sutter. “Is there anything beyond the universe?” space.com. May 02, 2021.) 

     

Conclusions

After a review of physics, I'm exhausted. I have reached the conclusion that the universe was not built for the human mind to understand … at least not fathomable for brains with small limitations like mine. Try as they may, astrophysicists cannot overcome my apparent nearsighted to science.

If only 5-10 percent of the universe is normal, observable matter, our picture of space is, in that sense, a direct product of the human mind. We are “blinded by being human when we look at something larger than the human experience,” explains Robert Lupton, Senior Research Astronomer at the Department of Astrophysical Sciences.

The universe emerged spontaneously from a random quantum fluctuation in some sort of primordial quantum vacuum,” some great intellect will say.

Upon hearing this explanation of origins, the vast majority of my fellow baby boomer friends and I will likely reply, “Far out!” Then, we will look quizzically into space as if searching for a simple interpretation and collectively scratch our old heads. At best, we would nod our wizened, gray noggins in a gesture of questionable tacit agreement.

Maybe a very intelligent man from the past had the really quintessential question for us to consider.

Gottfried Wilhelm Leibniz (1646–1716) was one of the great thinkers of the seventeenth and eighteenth centuries and is known as the last “universal genius.” Leibniz also bequeathed us calculus and the binary system at the heart of modern computers.

Lloyd Strickland, Professor of Philosophy and Intellectual History at Manchester Metropolitan University, relates …

"Leibniz went a step further, wondering why there is a universe at all. The question is a challenging one because it seems perfectly possible that there might have been nothing whatsoever – no Earth, no stars, no galaxies, no universe. Leibniz even thought that nothing would have been “simpler and easier.” If nothing whatsoever had existed then no explanation would have been needed – not that there would have been anyone around to ask for an explanation, of course, but that’s a different matter.

Leibniz thought that the fact that there is something and not nothing requires an explanation. The explanation he gave was that God wanted to create a universe – the best one possible – which makes God the simple reason that there is something rather than nothing.”

(Lloyd Strickland. “Answering the biggest question of all: why is there something rather than nothing?” The Conversation. November 11, 2016.)

In the centuries since Leibniz’s death, his great question has continued to exercise philosophers and scientists. Answers remain unclear. To me, only God knows the size of the universe. And, most importantly, only He – the eternal, the omnipotent, the omniscient – remains the Creator and the Sustainer of the universe and is unlimited with regard to knowledge, power, extension, and moral perfection. That's something I can wrap my old head around.

 

 
Leibniz’s “Characteristica Universalis,” the basis for his calculus ratiocinator

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