So now it turns out, what we call the observable universe — the portion observable within our cosmological horizon, a.k.a the final frontier — has at least 10 times moregalaxies than the mid-1990s Hubble Deep Field imageries sum to about 100 to 200 billion.

With the help of saved data from numerous deep space images from the Hubble Space Telescope and other telescopes, an international group of researchers led by Christopher Conselice from the University of Nottingham, UK, formed a 3D map of the known universe.

Mathematical models helped to compute for galaxies current telescopes cannot yet observe at the moment. These disclosed that, to make sense of the numbers and the maps, about 90% of galaxies are far, far away and too weak to be observed openly.

The map reconstructs, as perfectly as possible, diverse times in the universe’s history as far back in times as 13 billion years in its past. Therefore, when the cosmos was some billion years younger than today, it had 10 more galaxies per unit volume. Galaxies decline in number (and rise in size) as the billion years go by. 

Conselice explains, “This gives us a verification of the so-called top-down formation of structure in the universe,”

This helps answer Olbers’ Paradox (why the night sky is still dark, even with the billions of stars). The uncountable stars inside the billions of galaxies are imperceptible to the human eye because of redshifting of light, the cosmos’s dynamic nature, and interstellar dust and gas absorbing light. This keeps the night sky mostly dark.

Conselice explains further:

The growth of more progressive space telescopes in the future, starting with the James Webb Space Telescope (JWST) in 2018, would definitely help us see the observable cosmos clearly. Who knows what remains lurking just by that expanded frontier of space.

In any case, a larger known universe means an even wider space to accommodate the search for possible extraterrestrial life. Why not? Every time we think that we understand more of it, the universe seems to always surprise us with more.

Physicists have long studied the nature of the universe. But some go a step further into the unknown (and probably unknowable), contemplating what lies outside the boundaries of our universe. Is it possible that something else exists beyond existence? Yes. Here are five theories about what that "something" might be.

The "outside the universe" question gets tricky right off the bat, because first you have to define the universe. One common answer is called the observable universe, and it's defined by the speed of light. Since we can only see things when the light they emit or reflect reaches us, we can never see farther than the farthest distance light can travel in the time the universe has existed. That means the observable universe keeps getting bigger, but it is finite – the amount is sometimes referred to as the Hubble Volume, after the telescope that has given us our most distant views of the universe. We'll never be able to see beyond that boundary, so for all intents and purposes, it's the only universe we'll ever interact with.

 

Beyond the Hubble Volume: We know with some certainty that there's "more universe" out there beyond that boundary, though. Astronomers think space might be infinite, with "stuff" (energy, galaxies, etc.) distributed pretty much the same as it is in the observable universe. If it is, that has some seriously weird implications for what lies out there. Beyond the Hubble Volume you won't just find more, different planets. You will eventually find every possible thing.

Read that again and let it sink in. Everything. If you go far enough, you'll find another solar system with an Earth identical in every way except that you had cereal for breakfast this morning instead of eggs. And another where you skipped breakfast. And one where you got up early and robbed a bank. In fact, cosmologists think that if you go far enough, you will find another Hubble Volume that is perfectly identical to ours. There's another version of you out there mirroring your every action 10 to the 10^188 meters away. That may seem unlikely, but then, infinity is awfully infinite.

Dark Flow: In 2008, astronomers discovered something very strange and unexpected – galactic clusters were all streaming in the same direction at immense speed, over two million miles per hour. New observations in 2010 confirmed this phenomenon, known as Dark Flow. The movement defies all predictions about the distribution of mass throughout the universe after the Big Bang.

One possible cause: massive structures outside the Hubble Volume exerting gravitational influence. This would mean that the structure of the infinite universe beyond our view is not uniform. As for the structures themselves, they could be literally anything, from aggregations of matter and energy on scales we can barely imagine to bizarre warps funneling gravitational forces from other universes.

 

Infinite Bubbles: Talking about things outside the Hubble Volume might be a bit of a cheat, since it's still really the same universe, just a part of it we can't see. It would have all the same physical laws and constants. In another version of the story, the post-Big Bang expansion of the universe caused "bubbles" to form in the structure of space. Each bubble is an area that stopped stretching along with the rest of space and formed its own universe, with its own laws.

In this scenario, space is infinite, and each bubble is also infinite (because you can store an infinite number of infinities inside a single infinity). Even if you could somehow breach the boundary of our bubble, the space in between the bubbles is still expanding, so you'd never get to the next bubble no matter how fast you went.

Black Hole Spawning: A theory proposed by physicist Lee Smolin, known as the fecund universes theory, suggests that every black hole in our universe causes the formation of a new universe. Each universe will have slightly different physical laws than the forerunner universe. In this way, Smolin suggests a sort of natural selection for universes, as laws that lead to the frequent formation of black holes lead to the creation of more universes, while non-black hole forming universes "die out." This theory has since been discounted (by Smolin himself and others).

Many Parallel Universes: There are tons of theories about parallel universes, but the most accepted one these days involve an evolution of the ideas of string theory to involve membranes that vibrate in other dimensions. It's beyond the scope of this article to get too detailed about string or membrane theory, but the upshot of the whole thing is that these rippling membranes in the 11th dimension are whole other universes, and when the ripples slam into each other they form a new universe.

The effects of the rippling motion help explain the observed distribution of matter in our universe. One of the weirdest elements of the theory is the idea that all the gravity we experience in our universe is actually leaking into it from another universe in another dimension (which explains why gravity here seems so weak compared to the other fundamental forces).

The Hubble Space Telescope has been used to measure the phenomenon first observed by the astronomer after which it was named: the expansion of the universe. It is the most precise measurement of the rate of expansion yet made, and it confirms something that's been bothering astronomers for a while. The universe appears to be expanding faster than our measurements of the cosmic background radiation indicate it should be, suggesting either one of the measurements is wrong, or the expansion is being influenced by an unknown force.

As the universe expands, galaxies get further apart. Investigations into the way this is happening have been central to some of the most important discoveries in cosmology over the last century, but it seems we're not done yet.

We can precisely measure the rate at which a galaxy is moving away from us from how much the wavelength of its light has stretched (known as red shift). Measuring the distance is harder, relying on the brightness of specific stars and supernovas known as “standard candles”. Comparing their brightnesses can indicate distance.

NGC 3972 is one of the galaxies whose Cepheid variable stars were studied to help measure the expansion of the universe. NASA, ESA, A Reiss (STScl/JHU)

Using Hubble's more exact measurements of certain standard candles, a paper to be published in The Astrophysical Journal reports the Hubble constant, a measure of the expansion of the universe, as 67 (42 miles) kilometers per second per megaparsec. This means that for every additional million parsecs (3.3 million light-years) away from us a galaxy is, its speed increases by 67 kilometers (42 miles) per second.

The problem is this figure is 9 percent larger than the value we calculate using observations of the situation shortly (378,000 years being "shortly" to cosmologists) after the Big Bang. This is based on the Planck satellite's measurements of the cosmic background radiation created at that time, processed using models of how this should've changed as the universe evolved.

Previous estimates of the current Hubble constant had also been higher than that derived from the Planck data, but there was uncertainty in the measurements. Using new methods to calibrate the brightness of Cepheid variables, the standard candles used to measure relatively nearby galaxies, Hubble decreased its uncertainty range to 2.3 percent. Getting the Hubble constant accurate to within 10 percent was one of Hubble's original goals, so this dramatically exceeds that. With this newfound precision, the chance of the current and early universe expansions aligning drops to one in 5,000, which seems a bit low to rely on.

Three steps astronomers used to measure the universe's expansion rate: 1) Using Hubble to measure the distances of stars called Cepheid variables, via parallax. 2) Applying the calibrations from these to Cepheids in nearby galaxies that have recently hosted Type Ia supernovas. 3) Knowing the distances to these supernovas, calibrating this to measure the distances to galaxies so distant we can't see the Cepheids. NASA, ESA, A. Feild (STScl), and A. Reiss (STScl/JHU)

"Both results have been tested multiple ways, so barring a series of unrelated mistakes, it is increasingly likely that this is not a bug but a feature of the universe," said Professor Adam Riess of the Space Telescope Science Institute. Riess shared the 2011 Nobel Prize in physics for his discovery that the universe's expansion is accelerating, not slowing down, leading to the acceptance of the idea of dark energy.

If both measurements are right, then our understanding of the laws of physics at large scales needs an overhaul. Several possible explanations have been proposed, but at this stage, we have little basis for choosing any of them.

One holds that dark energy, the force causing the universe's expansion to accelerate, is itself accelerating. That is, the universe isn't just growing faster, but growing faster at an increasing rate, like a skier going from a gentle slope to a steadily steeper downhill run. Given how little we know about dark energy, we can't rule this out.

Another idea posits a currently undetected subatomic particle, affected by gravity but immune to the other three fundamental forces. Known as a sterile neutrino, such a particle would travel close to the speed of light, affecting how the universe evolves.

The observations could also be explained if astronomers have underestimated the interactions between dark matter, which we know of from the rotation rate of galaxies but don't fully understand, and the directly observable parts of the universe.

Each of these theories, if correct, would interfere with the models we use to apply the data from the early universe to today's situation. They'd also keep many theoretical physicists busy for years trying to explain the implications.

Article was originally published on iflscience.

Astronomers used telescopes in space and on the ground to examine five galaxies – leading them to arrive at an independent measurement of the Hubble constant.

This new measurement is challenging the way we understand the universe, as it could possibly point toward new physics beyond our current knowledge.

The theory that the universe is expanding is widely accepted by astronomers. It’s believed that this expansion happens at a constant rate, known as the Hubble constant, which is considered to be one of the fundamental quantities that describe our universe. However, this rate of expansion has been the subject of many studies, each presenting their own measurement of the Hubble constant.

One recent study offers another measurement of the Hubble constant. Astronomers from the H0LiCOW collaboration led by Sherry Suyu used telescopes in space and on the ground, including the NASA/ESA Hubble Space Telescope, to examine five galaxies – leading them to arrive at this independent measurement of the Hubble constant.

The five massive galaxies the study observed were located between the Earth and very distant quasars. These quasars are very luminous and the light they emit tends to bend around the huge masses of the galaxies due to strong gravitational lensing, which creates multiple background images of the quasar that usually smear into arcs.

“Our method is the most simple and direct way to measure the Hubble constant as it only uses geometry and General Relativity, no other assumptions,” said co-lead researcher Frédéric Courbin. The team measured the delays between the flickers of these different images of the quasars, which are directly related to the Hubble constant.

Using the time delays between the multiple images and computer models, the team arrived at an incredibly precise (at a 3.8 percent rate) measurement of the Hubble constant.  “An accurate measurement of the Hubble constant is one of the most sought-after prizes in cosmological research today,” said researcher Vivien Bonvin.

The measurement Suyu and her team arrived at agrees with other measurements of the Hubble constant in the local universe that relied on Cepheid variable stars and supernovae as points of reference. These measurements, however, differ in value with those made by the ESA Planck satellite. This is to be expected because Planck measured the Hubble constant by observing the cosmic microwave background for the early universe.

“The expansion rate of the universe is now starting to be measured in different ways with such high precision that actual discrepancies may possibly point towards new physics beyond our current knowledge of the universe,” Suyu explained. The values acquired by groups of astronomers for the local universe — the region of the nearby universe that stretches about 1 billion light years in radius — seem to disagree with the accepted theoretical model of the universe.

This new measurement of the Hubble constant is challenging the way we understand the universe. It’s not surprising, though, especially since there’s still a lot we don’t understand about our home. “The Hubble constant is crucial for modern astronomy as it can help to confirm or refute whether our picture of the universe — composed of dark energy, dark matter and normal matter — is actually correct, or if we are missing something fundamental,” Suyu further explained.

References: Spacetelescope, NASA

Article was originally published on Futurism.

Though the universe is only 13.8 billion years old, it is also 93 billion light-years wide, which confuses some because nothing is supposed to be able to travel faster than the speed of light. However, the confusion can be cleared up by reexamining the Theory of Relativity.

The speed of light is one of the most important and fundamental properties of our universe. It’s used to measure distances, for interplanetary communications, and in various mathematical calculations. And that’s just the start of it.

The speed at which light travels through a vacuum — 299,792 kilometers (186,282 miles) per second — is static and unchanging. If you remove that constant, the very foundation of modern physics crumbles due to a number of reasons, and the general rule can be summed up with this: Nothing in the universe can travel faster than the speed of light.

As you can imagine, some confusion arises when one considers the fact that the universe is not 13.8 billion light-years across — a number that corresponds with the age of the universe. By current estimates, it’s actually quite a bit larger with an estimated diameter of some 93 billion light-years. And that’s just what we can see. What we can’t see may go on forever.

So, how can the universe be 93 billion light-years wide if it is only 13.8 billion years old and nothing can travel faster than light?

Before you can understand why the universe’s size is so much greater than its age, it is important to understand just how light works.

Sir Isaac Newton was unquestionably one of the greatest minds to ever live. In addition to “inventing” calculus, he was the first scientist to truly understand the essence of light and what happens when you break it into its constituent parts.

For starters, his research revealed that black is the absence of color, while white light — like that which comes from the Sun and other stars — is a combination of every color. By looking at an object’s light through a prism, one can see the corresponding elements the light represents, which can then be used to help determine the object’s composition, temperature, and even where it is in the evolutionary process.

In more ways than one, Newton’s work revolutionized physics and paved the way for all of the greats, including Niels Bohr, Max Planck, and, of course, Albert Einstein. For the purposes of this discussion, however, the most relevant scientist to build off Newton’s work went by the name of Christian Doppler.

Doppler came to prominence hundreds of years after Newton’s death, and if you aren’t familiar with his work, he discovered something that is now called the Doppler effect. This process explains why some light from cosmic sources tends to land near the red end of the electromagnetic spectrum while some light is closer to the blue end.

In simple terms, the Doppler effect notes how the wavelength of light is shifted based on the direction that the source is moving, like whether something is coming toward us or moving away. Specifically, light waves will be stretched if the source is moving away from the observer, thus appearing red (the longer wavelength). Conversely, the light waves will be compressed if the object is heading toward the observer, thus appearing blue (the shorter wavelength).

Along the way, a game-changer presented itself. Ultimately, almost all galaxies appeared to be shifting toward a longer wavelength, which meant that they looked red, like they were moving away from us. Even more astoundingly, not only was most everything moving away from us, this redshift was increasing, meaning that the objects were moving away from us faster and faster.

This led to the discovery that the universe is not stationary, as some believed it to be — it’s actually expanding!

Here’s where things get sticky. Our observations of redshift revealed that objects three times more distant are moving three times faster relative to nearby galaxies. The farther we look into space, the faster the galaxies are moving — in fact, they’re moving so fast at these vast distances that they easily surpass the speed of light. However, as previously stated, the speed of light is the universal speed limit. So how can this be?

First, note that while there is a limit to what we can see, the actual universe extends much farther than we can comprehend. Everything within this limit is called the “observable universe,” and it includes:

1) 10 million superclusters

2) 25 billion galaxy groups

3) 350 billion large galaxies

4) 7 trillion dwarf galaxies

5) 30 billion trillion (3×10²²) stars

If all of this was tucked into 13.7 billion light-years of spacetime, the universe would seem pretty packed.

The first problem with the assumption that the universe’s size should be equal to its age in years based on the distance light travels arrives when we look at the first few moments that followed the Big Bang.

When the universe first “popped” into existence approximately 13.75 billion years ago, spacetime itself began expanding at speeds faster than the speed of light. This period, called inflation, is integral in explaining much more than the universe’s size. It also covers things like the homogeneous nature of space on a large scale and the conditions that existed during the first epoch.

Basically, the universe transitioned from an infinitely dense and hot state into a vast area teeming with protons and neutrons — particles that eventually came together and forged the building blocks of all matter — within moments. After the initial inflation died down, the expansion slowed. Now, objects are being pulled apart by a mysterious force called dark energy.

Through means that haven’t yet been ascertained, this expansion does appear to be happening faster than the speed of light, but that doesn’t mean what you probably think it does.

I’m afraid the confusion stems from a basic misinterpretation of relativity itself. You see, the theory states that objects cannot travel faster than the speed of light through spacetime. It doesn’t, however, place any limits on spacetime itself.

So, to summarize, the size of space does not conflict with basic physics.

Essentially, the galaxies themselves (and any other objects in space) aren’t breaking any laws, because they aren’t traveling through space faster than light (at least, not in the traditional sense). Rather, every portion of space is expanding and stretching. It’s not even that the edges are flying outward, but that spacetime itself — the area between galaxies, stars, planets, you and I — is stretching.

In short, spacetime is expanding and pushing matter apart. Matter is not really traveling through spacetime.

As an interesting aside, unfortunately, the expansion has some bleak implications for the future of the universe. Assuming the expansion continues indefinitely (and doesn’t slow), the horizon of the visible universe will gradually shrink until objects will simply be too far apart for light from one galaxy to ever reach another.

For that matter, much of what we see now was originally much closer. Thanks to the expansion, these objects have been carried off, and some galaxies and other objects have been red-shifted out of existence (or out of our view, anyways). The most distant galaxies are among the oldest things in the universe, having formed when the universe was just millions of years old, and it’s likely a majority of them no longer exist or are located in a completely different section of the cosmos today.

References: MSU, Einstein Online