Big Bang
esiegel | October 12, 2017"It’s hard to build models of inflation that don't lead to a multiverse. It’s not impossible, so I think there’s still certainly research that needs to be done. But most models of inflation do lead to a multiverse, and evidence for inflation will be pushing us in the direction of taking [it] seriously." -Alan Guth
It sounds like an unprovable fantasy: the idea that our Universe is just one of countless others, dotted across an eternally expanding empty space separating them. That’s generally how we picture the Multiverse, with each Universe having its own hot Big Bang distinct from every…
esiegel | September 27, 2017"I know of no other scientist, no other theoretical physicist alive who has a clearer focus on whether our theories and ideas are relevant to the real world. And that's always what he's after." -Neil Turok, on Paul Steinhardt
The inflationary Universe is one of the most revolutionary new ways of looking at the cosmos to come out of the last 40 years of science. Instead of going all the way back to a singularity from which time, space, matter, and energy all emerged, cosmic inflation posits a different state that gave rise to our hot, dense, matter-and-radiation-filled Universe. With energy…
esiegel | September 22, 2017“The more clearly we can focus our attention on the wonders and realities of the universe about us, the less taste we shall have for destruction.” -Rachel Carson
The idea that the spatial fabric of the Universe itself is expanding, and that’s what’s behind the observed relationship between redshift and distance has long been controversial, and also long-misunderstood. After all, if more distant objects appear to recede more quickly, couldn’t there be a different explanation, like an explosion that flung many things outward? As it turns out, this isn’t a mere difference in interpretation,…
esiegel | September 21, 2017"Despite its name, the big bang theory is not really a theory of a bang at all. It is really only a theory of the aftermath of a bang." -Alan Guth
Did the Universe begin with the Big Bang? When we discovered the cosmic microwave background, and its properties matched exactly the prediction of the Big Bang theory, it was a watershed moment for cosmology. For the first time, we had uncovered the origins to the entire Universe, having learned where all of this came from at long last. Emerging from a hot, dense, expanding, and cooling state, the matter-and-radiation-filled early Universe gave…
esiegel | July 18, 2017"The design of the universe...is very magnificent and shouldn’t be taken for granted." -Charles W. Misner
One of the more puzzling aspects of our Universe is that, no matter which direction we look in, no matter how far away we check, its properties appear to be practically identical. This is surprising, since no signal can reach from one disconnected region to another, and yet the Universe behaves as if everything began from the same initial state. We refer to this as the horizon problem.
If these three different regions of space never had time to thermalize, share information or transmit…
esiegel | July 14, 2017“Gamow was fantastic in his ideas. He was right, he was wrong. More often wrong than right. Always interesting; … and when his idea was not wrong it was not only right, it was new.” -Edward Teller
100 years ago, our conception of the Universe was so small it's almost laughable. We still were mired in Newtonian thought, conceiving only of the stars within our own Milky Way, with a Universe that was perceived as static and unchanging, and where the stars which made it up perhaps even lived forever. Yet today, we have a Universe that's expanding, cooling, full of dark matter and dark energy, and…
esiegel | July 11, 2017"In the current cosmological model, only the three lightest elements were created in the first few minutes after the Big Bang; all other elements were produced later in stars." -Fumagalli, O'Meara and Prochaska, 2011
When it was first conceived, the idea of the Big Bang was spectacular for the fact that it made three incredibly distinct predictions, ranging from the largest scales down to the smallest. As we looked from million to billions of light years away, we should find that the Universe expands at a rate that changes depending on what’s in it; there should be a leftover, uniform glow in…
esiegel | July 6, 2017“There are two infinities that confuse me: the one in my soul devours me; the one around me will crush me” -Gustave Flaubert
Last week, Donald Trump restored the National Space Council, promising to take America and the world to new heights in space. He also made some statements claiming that this is infinity here, and that we don’t know, but it could be infinity. In both cases, the statements don’t quite match the facts, as the funding cuts proposed by the President are inconsistent with increased exploration efforts, and, more to the point, we know we’ll never access infinity.
Looking back…
esiegel | June 30, 2017"By its very nature science knows no boundaries. Walling off any group, for any reason, from full participation damages the entire enterprise of science. We must be scientists without borders." -Rocky Kolb
We normally think of “let there be light” as when the Universe got its start. In a particular sense, this is true, since you can go back to a time before stars and galaxies existed, when the Universe was only a few million years old or less. But even before the first star, there was still light.
According to the original observations of Penzias and Wilson, the galactic plane emitted some…
esiegel | June 4, 2017“It is the function of science to discover the existence of a general reign of order in nature and to find the causes governing this order. And this refers in equal measure to the relations of man - social and political - and to the entire universe as a whole.” -Dmitri Mendeleev
When the Big Bang first occurred, the Universe was filled with all the various particles and antiparticles making up the Standard Model, and perhaps still others yet to be discovered. But missing from the list were protons, neutrons, or any of the atomic nuclei key to the life-giving elements in our Universe today.…
esiegel | May 27, 2017"The Edge... there is no honest way to explain it because the only people who really know where it is are the ones who have gone over." -Hunter S. Thompson
When we look at the nearby Universe, it looks a lot like we, ourselves, appear. Nearby galaxies are similar in structure to our own; the stars inside them have the same properties, masses, ages and distributions as our own. But as we look to greater and greater cosmic distances, we find that more distant galaxies appear younger, bluer, smaller, and less evolved. If we go back beyond a certain point, there are no more galaxies at all.…
esiegel | May 16, 2017"Logic takes care of itself; all we have to do is to look and see how it does it." -Ludwig Wittgenstein
There are a great many events that occurred to give rise to the world, the Universe, and you. Everything from the Big Bang to the existence of the laws of physics to the cosmic history that created Earth to the biological history that gave rise to the 7+ billion of us today needed to unfold exactly as it did in order for things to be the way they are today.
A standard cosmic timeline of our Universe's history. A series of extremely unlikely events all needed to occur in order so that you…
esiegel | May 11, 2017“…an understanding of the infinite tree of universes seems to be needed in order to make statistical predictions about the properties of our own universe, which is assumed to be a typical “branch” on the tree.” -Alan Guth
The Big Bang is commonly regarded as the start of it all, but that's only the birth of what we call our observable Universe. There must have been something compelling to set it up, complete with the initial conditions that our Universe began with. An idea called Cosmic Inflation fits the bill perfectly, providing those conditions and making six explicitly new predictions.…
esiegel | May 6, 2017“Despite its name, the big bang theory is not really a theory of a bang at all. It is really only a theory of the aftermath of a bang.” -Alan Guth
When we look to the deepest reaches of space, we can look for the “first” of any type of object. The first galaxy, the first star, the first light from the CMB, or even the first signals from the Big Bang, like gravitational waves. Yet these signals all have very different redshifts from one another, and perhaps more puzzlingly, lie at extraordinarily different cosmic distances from us.
Looking towards the north pole of the Milky Way galaxy, we…
esiegel | April 15, 2017"Entropy shakes its angry fist at you for being clever enough to organize the world." -Brandon Sanderson
The universe was born hot, dense, expanding, full of matter, antimatter and radiation... and in a low-entropy state. If entropy is a measure of disorder, though, that sure does sound like an awfully high-entropy state, not a low-entropy one. So why, when we talk about the Universe, do we say that the early Universe had such low entropy?
Our Universe, from the hot Big Bang until the present day, underwent a huge amount of growth and evolution, and continues to do so. Image credit: NASA /…
esiegel | March 24, 2017"The creation of something new is not accomplished by the intellect but by the play instinct acting from inner necessity. The creative mind plays with the objects it loves." -Carl Jung
13.8 billion years ago, the Universe as we know it came into existence. Today, the part we can observe is 46 billion light years in radius, having grown tremendously thanks to the expansion of the Universe. But if we extrapolate that backwards, we find that the Universe couldn’t have been infinitely small at the moment of its birth, but rather was a finite size at all finite times.
The size of the Universe (y-…
esiegel | March 17, 2017“We are told to let our light shine, and if it does, we won’t need to tell anybody it does. Lighthouses don’t fire cannons to call attention to their shining- they just shine.” -Dwight L. Moody
The farther away in space we look, the farther back in time we’re seeing. Light arriving from a star ten light years away is ten years old; light that took a billion-year journey from a distant galaxy is a billion years old. If we look out today at the most distant light we can see, we discover that it originates from the Big Bang itself: the Cosmic Microwave Background, or CMB.
The timeline of our…
esiegel | February 17, 2017"It is the function of science to discover the existence of a general reign of order in nature and to find the causes governing this order. And this refers in equal measure to the relations of man - social and political - and to the entire universe as a whole." -Dmitri Mendeleev
When the Universe was first born, all we had was hydrogen and helium, with a trace amount of lithium and absolutely nothing else. 13.8 billion years later, hydrogen is still #1 in the Universe and helium is still #2, but lithium isn’t close to #3 anymore: more than two dozen elements have passed it. The key? Stars!…
esiegel | February 11, 2017“I want to stand as close to the edge as I can without going over. Out on the edge you see all the kinds of things you can’t see from the center.” -Kurt Vonnegut
We all know how explosions work: a tremendous release of energy causes a rapid outward expansion, and the most energetic particles get flung the farthest and at the greatest speeds. Things fly apart, spread out, and wind up a tremendous distance away. And within our Universe, nothing has ever released more energy than the event that started it all: the Big Bang.
An explosion in space would have the outermost material move away the…
esiegel | February 10, 2017"To know that we know what we know, and to know that we do not know what we do not know, that is true knowledge." -Nicolaus Copernicus
As we peel back the layers of information deeper and deeper into the Universe’s history, we uncover progressively more knowledge about how everything we know today came to be. The discovery of distant galaxies and their redshifts led to expanding Universe, which led to the Big Bang and the discovery of very early phases like the cosmic microwave background and big bang nucleosynthesis.
The history of the Universe, as far back as we can see using a variety of…