Our universe exists on a mind-blowing scale, so big that preparing any number of space facts does not do our cosmos justice. It’s so large that there are black holes that dwarf our sun by factors of billions, there are pulsars that stretch thousands of light-years into infinity, and nebulae (such as lyman-alpha blobs) that are known as some of the largest objects in our universe.
There’s a lot to know about space, including the un-known. So we’ve provided this list to help tease your brain and provide new and interesting perspectives on our scientific measurement of stellar phenomena.
Without further adieu, here is a look at 50 mind blowing space facts.
- Venus is the hottest planet in our solar system. This is contrary to the idea that Mercury, the innermost planet in our solar system would be the hottest.
- The Earth’s moon is approximately 4.5 billion years old.
- One million earth sized objects could fit within the Sun.
- The Sun is nearly a perfect sphere. It has only a 10 kilometre difference in its polar diameter compared to its equatorial diameter.
- Saturn has 150 moons and smaller moonlets.
- The Milky Way is known as a barred spiral galaxy.
- The Oort cloud is made up of a reserve of planetesimals (small comets and debris) that date back to the birth of our solar system
- The ‘cosmic web’, the entire fabric of our cosmos, is known as the biggest thing in our universe
- When the Earth is at it’s closest approach to the sun, it’s known as the “perihelion”, when at it’s furthest, it’s known as the “aphelion”.
- Apollo 11 through 14 astronauts had to be quarantined on their return back to Earth.
- Uranus makes it’s trip around the sun once ever 84 Earth years.
- Only one spacecraft has flown by Neptune, and that was the Voyager 2 craft in 1989.
- The Milky Way contains a super-massive black hole at the center known as the Sagittarius A* star. It is believed all active galaxies contain a black hole at their cores.
- The Sun is 149.6 million km (or 92 million miles) from the Earth.
- One year on Mercury is equivalent to 88 Earth days.
- One year on Jupiter is equivalent to 12 Earth years.
- Saturn is 1.2 billion km away from Earth at the closest orbital point, and 1.67 billion km away at the furthest point.
- The orbit of comets is for the most part, elliptical.
- Your would weigh 38% of your total mass on Mercury.
- Venus is the second brightest object in the night sky.
- Mars is home to the tallest mountain in the solar system, Olympus Mons.
- Jupiter has the shortest day of all the planets at 9 hours and 55 minutes.
- Jupiter’s great red spot is a storm that has circulated for more than 350 years.
- Jupiter’s great red spot is so large that you could fit three Earths within.
- The Andromeda Galaxy is our nearest galactic neighbour.
- A total solar eclipse only occurs every 1-2 years.
- The longest in which a solar eclipse can last, is seven and a half minutes.
- Pluto was re-classified to a dwarf planet (from being considered a planet) in 2006.
- Pluto has only been visited by one spacecraft, New Horizons.
- Jupiter’s moon Io has volcanic eruptions.
- Mars has the longest valley in our solar system. Valles Marineris is 2,500 miles (4,000 km) long and can be seen from space.
- Mercury and Venus are the only planets in our solar system without moons.
- The Milky Way is approximately 100,000 light-years wide.
- One day on Mars is 24 hours, 39 minutes, and 35 seconds long.
- Venus is the only planet that spins in the opposite direction of all other planets.
- Venus has more active volcanoes than any other planet in our solar system.
- Pluto owns a hazy atmosphere that extends 1,000 miles (1,600 km) above it’s surface.
- Neptune radiates more heat than it absorbs from the Sun.
- The area around the sun (the solar atmosphere) is actually far hotter than the sun itself. The Sun burns at 10,000 degrees Fahrenheit whereas the upper atmosphere can reach millions of degrees.
- Pluto is smaller than the Earth’s moon.
- The Andromeda galaxy is the furthest object you can spot with the naked eye.
- Mars has the largest dust storms in the solar system. These storms can last for months and cover the entire planet.
- Pieces of Mars have actually fallen to Earth. Scientists have found microscopic fragments of martian atmosphere on our planet (likely brought to Earth via meteorite).
- The point of no return around a black-hole is known as the event horizon.
- Any free-moving liquid will form into a sphere in outer space thanks to its surface tension.
- The revolution of the Earth increases annually by roughly 0.0001 seconds
- The International Space Station (ISS) circles the Earth every 90 minutes.
- The number of stars in the Milky Way is estimated at 200,000,000,000.
- Britain has only launched one satellite, known as the Black Arrow.
- Pluto, is named after the Greek God of the underworld (previously known as Hades).
According to astronomers, the Milky Way is a bit of a loner.
A new study presented at the american astronomical society and two subsequent papers published in the Astrophysical Journal detail evidence that our region of the universe has fewer planets, stars, galaxies, and matter than other regions.
The void that our galaxy lives is known as KBC and it’s the largest void we’ve ever found. KBC (named after discoverers Keenan, Barger, and Cowie), is seven times larger than the average galactic void, measuring 1 billion light-years.
The idea that we live in this void is a handy explanation for problems with the Hubble Constant. The Hubble Constant is the unit of measurement used to describe the expansion of the universe. It’s called the ‘constant’ because the rate of expansion should be the same at every point in the universe, but it isn’t – which suggests that there are varying gravitational forces all over the universe.
“No matter what technique you use, you should get the same value for the expansion rate of the universe today. Fortunately, living in a void helps resolve this tension.”
Understanding our place in these voids is integral to learning about the large scale structure of our universe. Our universe is described as “Swiss cheese-like in the sense that it is composed of “normal matter” in the form of voids and filaments. The filaments are made up of superclusters and clusters of galaxies, which in turn are composed of stars, gas, dust and planets. Dark matter and dark energy, which cannot yet be directly observed, are believed to comprise approximately 95 percent of the contents of the universe.”
The latest findings show quite evidently that our galaxy lives in a much larger than average sized void which importantly highlights the differential rates at which our universe is expanding. It’s an important find that will aid astronomers in deciphering the structure of our cosmos.
(Reuters) – Scientists have for a third time detected ripples in space from black holes that crashed together billions of light years from Earth, a discovery that confirms a new technique for observing cataclysmic events in the universe, research published on Thursday shows.
Such vibrations, known as gravitational waves, were predicted by Albert Einstein more than 100 years ago and were detected for the first time in September 2015. They are triggered by massive celestial objects that crash and merge, setting off ripples through space and across time.
The latest detection occurred on Jan. 4, 2017. Twin lasers in Louisiana and Washington picked up the faint vibrations of two black holes that were 20 and 30 times more massive than the sun, respectively, before they spiraled toward each other and merged into a larger black hole.
The discovery marks a turning point in the nascent field of gravitational-wave astronomy, which scientists are developing to learn more about how the universe formed. The first detection of gravitational waves created a scientific sensation.
“We’re really moving from novelty to a new observational science,” said Massachusetts Institute of Technology astrophysicist David Shoemaker.
A team of more than 1,000 scientists published their findings in this week’s issue of Physical Review Letters.
Like the previous two detections, the gravitational waves discovered in January slightly jiggled the L-shaped, 2.5 mile-long (4 km) laser beams that comprise the heart of the Laser Interferometer Gravitational-Wave Observatory, or LIGO.
By matching the shape of the waves with computer models, scientists confirmed the collision took place about 3 billion light years from Earth, twice as far as previous detections.
Black holes are regions so dense with matter that not even photons of light can escape their gravitational pull.
Analysis shows the pair likely were spinning in different directions before merging, a clue that they formed separately in a dense cluster of stars, sank to the core of the cluster and then paired up, Georgia Institute of Technology physicist Laura Cadonati told reporters during a conference call.
A second gravitational wave observatory in Italy is scheduled to begin operations this summer and will enhance LIGO’s ongoing studies. Scientists eventually expect to be able to find black holes merging about once a day.
They also are on the hunt for other objects, including colliding neutron stars, which are the dense remnants of collapsed stars so packed with matter that a single teaspoon would weigh 10 million tons on Earth.
(Reporting by Irene Klotz in Cape Canaveral, Fla.; Editing by Colleen Jenkins)
Scientists have a love-hate relationship with anomalies. On the one hand, science is the attempt to bring rational order to the chaos of possible explanations, models, and interpretations for what we see when we look out into the great void that is space. Such is the case of another great void in the cosmic background radiation that pervades the entirety of the known universe. The background radiation, according to standard cosmological models, should be, for the most part, evenly distributed and consistent across space, but there is one blot or void in which there is less cosmic radiation than anywhere else, and it stands out because it is unlike any other spot in the known universe.
Many explanations have proliferated as a result of the anomaly, and one of the most intriguing of these is the possibility that the void represents a collision between two parallel universes. While the notion of parallel universes has occupied the imagination of both scientists and science fiction writers alike, it has often been met with skepticism in the scientific community. One of the major reasons for that is because a sound scientific theory must offer the possibility of being testable. With anomalies like the “Cold Spot” that dismissal may not be as damning as once thought.
However, there may be one catch to the “many worlds” interpretation that fundamentally changes how we perceive all those different worlds. Howard Wiseman, a Harvard physicist, says that our understanding of the “many worlds” interpretation is a bit off:
“The problem with the many worlds interpretation is that it’s fuzzy,” said Wiseman. “Simply put, we cannot count the number of worlds that exist at any point in time. This makes the whole notion very hard to reconcile with the claim that these worlds are real.”
“In our theory, all other worlds are as real as our world, and they’ve all been around since the beginning of time,” Wiseman said. “The only mystery is what particular world we occupy.”
The first direct detection of gravitational waves, a phenomenon predicted by Einstein’s 1915 general theory of relativity, was reported by scientists in 2016.
Armed with this “discovery of the century”, physicists around the world have been planning new and better detectors of gravitational waves.
Physicist Professor Chunnong Zhao and his recent PhD students Haixing Miao and Yiqiu Ma are members of an international team that has created a particularly exciting new design for gravitational wave detectors.
The new design is a real breakthrough because it can measure signals below a limit that was previously believed to be an insurmountable barrier. Physicists call this limit the standard quantum limit. It is set by the quantum uncertainty principle.
The new design, published in Nature magazine this week, shows that this may not be a barrier any longer.
Using this and other new approaches may allow scientists to monitor black hole collisions and “spacequakes” across the whole of the visible universe.
How gravitational wave detectors work
Gravitational waves are not vibrations travelling through space, but rather vibrations of space itself. They have already told us about an unexpectedly large population of black holes. We hope that further study of gravitational waves will help us to better understand our universe.
But the technologies of gravitational wave detectors are likely to have enormous significance beyond this aspect of science, because in themselves they are teaching us how to measure unbelievably tiny amounts of energy.
Gravitational wave detectors use laser light to pick up tiny vibrations of space created when black holes collide. The collisions create vast gravitational explosions. They are the biggest explosions known in the universe, converting mass directly into vibrations of pure space.
It takes huge amounts of energy to make space bend and ripple. Our detectors – exquisitely perfect devices that use big heavy mirrors with scarily powerful lasers – must measure space stretching by a mere billionth of a billionth of a metre over the four kilometre scale of our detectors. These measurements already represent the smallest amount of energy ever measured.
But for gravitational wave astronomers this is not good enough. They need even more sensitivity to be able to hear many more predicted gravitational “sounds”, including the sound of the moment the universe was created in the big bang.
This is where the new design comes in.
A spooky idea from Einstein
The novel concept is founded on original work from Albert Einstein.
In 1935 Albert Einstein and co-workers Boris Podolsky and Nathan Rosen tried to depose the theory of quantum mechanics by showing that it predicted absurd correlations between widely spaced particles.
Einstein proved that if quantum theory was correct, then pairs of widely spaced objects could be entangled like two flies tangled up in a spider’s web. Weirdly, the entanglement did not diminish, however far apart you allowed the objects to move.
Einstein called entanglement “spooky action at a distance”. He was sure that his discovery would do away with the theory of quantum mechanics once and for all, but this was not to be.
Since the 1980s physicists have demonstrated time and again that quantum entanglement is real. However much he hated it, Einstein’s prediction was right and to his chagrin, quantum theory was correct. Things at a distance could be entangled.
Today physicists have got used to the “spookiness”, and the theory of entanglement has been harnessed for the sending of secret codes that cannot be intercepted.
Around the world, organisations such as Google and IBM and academic laboratories are trying to create quantum computers that depend on entanglement.
And now Zhao and colleagues want to use the concept of entanglement to create the new gravitational wave detector’s design.
A new way to measure gravitational waves
The exciting aspect of the new detector design is that it is actually just a new way of operating existing detectors. It simply uses the detector twice.
One time, photons in the detector are altered by the gravitational wave so as to pick up the waves. The second time, the detector is used to change the quantum entanglement in such a way that the noise due to quantum uncertainty is not detected.
The only thing that is detected is the motion of the distant mirrors caused by the gravitational wave. The quantum noise from the uncertainty principle does not appear in the measurement.
To make it work, you have to start with entangled photons that are created by a device called a quantum squeezer. This technology was pioneered for gravitational wave astronomy at Australian National University, and is now an established technique.
Like many of the best ideas, the new idea is a very simple one, but one that took enormous insight to recognise. You inject a miniscule amount of squeezed light from a quantum squeezer, and use it twice!
Around the world physicists are getting ready to test the new theory and find the best way of implementing it in their detectors. One of these is the GEO gravitational wave detector at Hannover in Germany, which has been a test bed for many of the new technologies that allowed last year’s momentous discovery of gravitational waves.
This is an article from Curious Kids, a new series aimed at children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!
Does space go on forever? – Conrad, age 6, Sydney.
Space probably does go on forever, but the truth is we don’t know. Not yet anyway. That’s what makes this a great question, because science is all about finding answers to things we don’t know yet.
So, what do we know about space? We know it’s big, really big. It’s big enough to contain the Earth and all the other planets. It’s big enough to include the Sun and all the stars we see at night.
Not that long ago, people thought that when they looked up at the night sky, they were seeing all of space. That was until Edwin Hubble came along. He was an American astronomer and what he found out was so amazing that NASA named the famous Hubble Space Telescope after him.
Stars far, far away
Almost 100 years ago, Hubble, the astronomer, was looking at some small fuzzy patches of light hidden among all the stars we can see. No one was exactly sure what they were, but Hubble discovered that these patches of light were made of stars and even more importantly, they were a long way away.
With that one discovery, our idea of space exploded.
The stars we see in the night sky are part of the Milky Way Galaxy. That’s the galaxy we belong to.
The patches of light that Hubble was studying were other galaxies – each one filled with stars and planets and lots of other things too. Some galaxies are smaller than our Milky Way and others are larger.
Space was a whole lot bigger than anyone had ever imagined.
How to see forever?
Space is big, but does it go on forever? The problem is we can’t see forever. There’s a limit to how much space we can see, just like we can’t step outside our front door and see every city in Australia.
The part of space we can see is called the observable universe. It contains all the light we will ever be able to see (because when we look across space we are mostly looking for light).
The observable universe can even be measured. It is 93 billion light years from one side to the other. Now that’s a distance even astronomers find hard to think about. It’s like making about 300,000 laps of our Milky Way Galaxy, yet our Sun has only made 20 laps in its entire life. Or can you imagine lapping the Earth 20 million trillion times?
What’s more, the observable universe is centred on us because we are at the centre, looking out into space. An alien on another planet, in a far away galaxy, would have their own observable universe. You might want to think of each of us being inside our own bubble universe.
If our two bubbles overlapped, then the alien would see some of the same things we can see. But what about the places that are outside our bubble? Would the alien see emptiness at the edge of space?
No, probably not. What’s more likely is they would see a part of space that we will never ever be able to see.
In theory space goes on and on…
So why do scientists think that space goes on forever? It’s because of the shape of space. Our part of space, or the observable universe, has a special shape: it is flat.
That means if you and a friend each had your own rocket ship and you both took off and travelled in a straight line, forever and forever, you would never meet. In fact, you would always stay exactly the same distance apart, within the observable universe.
But this is a really special case. If space was shaped any other way, then lots of things could happen. Your two rockets, travelling in a straight line, might eventually cross paths or they might get really close but never meet or perhaps they’d go the other direction and drift away from each other.
But only flat space will keep the rockets exactly apart.
When one idea solves lots of problems, scientists call it a theory. It means we could be on the right track to finding an answer.
The theory says that space must be really, really big but we can only see a small part of it, and that part looks special and flat. It’s kind of like how Earth seems flat, unless you are an astronaut floating in space. Up there, you see so much more of the Earth that it’s possible to see how it curves away.
My bet is that space does go on forever. Maybe one day science will help tell us if that’s true.
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The discovery of massive galaxy that stopped making any new stars by the time the Universe was only 1.65 billion years old means we may have to rethink our theories on how galaxies formed.
The galaxy, known as ZF-COSMOS-20115, formed all of its stars (more than three times as many as our Milky Way has today) through an extreme starburst event.
But it stopped forming stars to become a “red and dead” galaxy not much more than a billion years after the Big Bang. Such galaxies are common in our Universe today but not expected to have existed at this ancient epoch. Galaxies turn red when they stop forming stars due to the resulting absence of hot, blue stars that have very short lifetimes.
It is an incredibly rare find that poses a new challenge to galaxy evolution models to accommodate the existence of such galaxies much earlier in the Universe.
An earlier discovery
To put this discovery in context, I’d like to give a short, personal history of research on early massive galaxies.
In 2004 I wrote an uncannily similar Nature paper about the existence of massive, old galaxies in the early Universe that were discovered in deep near-infrared surveys. At that time we were peering back across space to 3 billion years after the Big Bang.
These were a challenge for the models of galaxy formation that scientists were working with at the time, the start of a period where our pictures of how galaxies formed were rapidly being rewritten.
At the time, a picture of galaxies forming by lots of mergers in hierarchical assembly was in vogue. The problem was that this meant that today’s massive galaxies were in little bits billions of years ago.
But significant changes were made – driven in part by observations of the abundance of early massive galaxies, the observations of large gas-rich disk galaxies at these epochs and the discovery of “red nuggets” – extremely compact massive elliptical galaxies which stopped forming stars early on.
We moved to a picture where most galaxy growth and formation was driven by the formation of stars within the galaxy itself, from cosmic gas coming in to the galaxy.
This gas is fed into galaxies along the cosmic web by cold streams that are effective early on and allow us to grow massive galaxies more quickly in the computer modelling.
Many, many astronomers contributed to these developments and it was fun to play a minor role.
The new discovery
Back in 2013, one of our students, Caroline Straatman of Leiden University, discovered a population of pale red dots in the ZFOURGE survey.
These dots were bright in the near-infrared but very faint in the 35 other wavelength bands we observed. This peak suggested the presence of roughly 500 million year old stars but at a huge cosmic redshift.
In the local Universe this peak appears in blue light, so the redshift points to a time around 1.5 billion years after the Big Bang. The light suggested that no young stars were present, and the near-infrared brightness suggested these were massive objects (1011 solar masses).
To put this in context, our Milky Way has been growing continuously for 12 billion years but is 3-5 times less massive.
Even more remarkably, the galaxies looked like ellipticals and were almost point sources, even with high-resolution Hubble Space Telescope observations. They were less than 5,000 light years across. Extremely dense red nuggets at an earlier time than anyone had suspected.
Lines in the spectrum
In 2012 a powerful new near-infrared spectrograph was commissioned on the W M Keck telescopes in Hawaii. Last year we used it to get a two-night exposure on some of these objects.
We were amazed when we got a spectrum of the brightest (and most massive). They showed the distinct signature of Balmer absorption lines of stars around 500 million years old. Importantly there was no sign of current star-formation.
This galaxy was already massive and between 500 million and 1 billion years old.
It must have formed extremely fast, and then its star formation died quickly. This extreme behaviour could require significant rewriting of our pictures of galaxy formation in the first billion years of cosmic history.
Why? Well, we think galaxies form in the centres of halos of cold dark matter. Dark matter particles is not made of ordinary atoms, and particle physicists are still trying to detect these in the laboratory.
These halos can form very early and act as seeds for galaxy formation giving it a kick start. Without dark matter it would be difficult to form any galaxy.
The problem is at this early time there are barely enough massive dark matter halos to accommodate such massive galaxies. As a consequence in simulated Universes we don’t find this population of non-star forming galaxies so early, nor do we find the massive ancestors with extreme star-formation rates a billion years earlier.
So, do we need two recipes for galaxy formation where some form extremely quickly and the rest take 12 billion years?
Time will tell. The history of this field has shown that the theoretical community has a very strong record of postdiction (as opposed to prediction), and I expect a slew of papers will turn up in the next few weeks to explain this object!
Teasing of theorists aside, galaxy formation is a very difficult field to work in; the astrophysics are complex and it is very much driven by new observations which is why it is so much fun to work in.
Meanwhile our groups are pursuing the quest for massive galaxies to even earlier times. We have designed new filters to identify these and hope to start a new survey using the Gemini telescopes this year. Theorists, get your predictions in now.
Astrophysicists from the University of Birmingham have made significant progress in understanding a key mystery of gravitational wave astrophysics – they mystery of how two black holes can collide together and merge.
On September 14 2015 at 5:51 am the first confirmed detection of gravitational waves occurred. It made waves the scientific community as it confirmed a major theory of Albert Einstein’s from 1915. In which his Theory of General Relativity believed that gravity travels through the cosmos in ‘waves’.
The researchers said they detected gravitational waves coming from two black holes – extraordinarily dense objects whose existence also was foreseen by Einstein – that orbited one another, spiraled inward and smashed together. They said the waves were the product of a collision between two black holes 30 times as massive as the Sun, located 1.3 billion light years from Earth.
The scientific milestone, announced at a news conference in Washington, was achieved using a pair of giant laser detectors in the United States, located in Louisiana and Washington state, capping a long quest to confirm the existence of these waves.
The announcement was made in Washington by scientists from the California Institute of Technology, the Massachusetts Institute of Technology and the LIGO Scientific Collaboration.
From the University of Birmingham:
In order for the black holes to merge within the age of the Universe by emitting gravitational waves, they must start out very close together by astronomical standards, no more than about a fifth of the distance between the Earth and the Sun. However, massive stars, which are the progenitors of the black holes that LIGO has observed, expand to be much larger than this in the course of their evolution. The key challenge, then, is how to fit such large stars within a very small orbit. Several possible scenarios have been proposed to address this.
The Birmingham astrophysicists, joined by collaborator Professor Selma de Mink from the University of Amsterdam, have shown that all three observed events can be formed via the same formation channel: isolated binary evolution via a common-envelope phase.
A new paper, published in Nature Communications, goes into detail on locating the source of the gravitational anomaly. Using a newly developed toolkit named COMPAS (Compact Object Mergers: Population Astrophysics and Statistics), the team was able to comprehend the results from the event.
Senior author Professor Ilya Mandel spoke on the issue: “This work makes it possible to pursue a kind of ‘palaeontology’ for gravitational waves. A palaeontologist, who has never seen a living dinosaur, can figure out how the dinosaur looked and lived from its skeletal remains. In a similar way, we can analyse the mergers of black holes, and use these observations to figure out how those stars interacted during their brief but intense lives.”
— UniBirmingham News (@news_ub) April 5, 2017
— BIGWaves (@UoBIGWaves) March 21, 2017
— Class. Quantum Grav. (@CQGplus) March 30, 2017
It follows the publication this month of a new look at supernovae in our universe, which the researchers say give only a “marginal detection” of the acceleration of the universe.
This seems to be a big deal, because the 2011 Nobel Prize was awarded to the leaders of two teams that used supernovae to discover that the expansion of the universe is speeding up.
But never have I seen such a storm in a teacup. The new analysis, published in Scientific Reports, barely changes the original result, but puts a different (and in my opinion misleading) spin on it.
So why does this new paper claim that the detection of acceleration is “marginal”?
Well, it is marginal if you only use a single data set. After all, most big discoveries are initially marginal. If they were more obvious, they would have been discovered sooner.
The evidence, so far
The supernova data alone could, at only a slight stretch, be consistent with a universe that neither accelerates nor decelerates. This has been known since the original discovery, and is not under dispute.
But if you also add one more piece of information – for example, that matter exists – then there’s nothing marginal about it. New physics is clearly required.
In fact, if the universe didn’t accelerate or decelerate at all, which is an old proposal revisited in this new paper, new physics would still be required.
These days the important point is that if you take all of the supernova data and throw it in the bin, we still have ample evidence that the universe’s expansion accelerates.
The pattern of galaxies isn’t actually random, so we used this pattern to effectively lay grid paper over the universe and measure how its size changes with time.
Using this data alone shows the expanding universe is accelerating, and it is independent of any supernova information. The Nobel Prize was awarded only after this and many other observational techniques confirmed the supernova findings.
Something missing in the universe
Another example is the Cosmic Microwave Background (CMB), which is the leftover afterglow from the big bang and is one of the most precise observational measurements of the universe ever made. It shows that space is very close to flat.
Meanwhile observations of galaxies show that there simply isn’t enough matter or dark matter in the universe to make space flat. About 70% of the universe is missing.
So when observations of supernovae found that 70% of the universe is made up of dark energy, that solved the discrepancy. The supernovae were actually measured before the CMB, so essentially predicted that the CMB would measure a flat universe, a prediction that was confirmed beautifully.
So the evidence for some interesting new physics is now overwhelming.
I could go on, but everything we know so far supports the model in which the universe accelerates. For more detail see this review I wrote about the evidence for dark energy.
What is this ‘dark energy’?
One of the criticisms the new paper levels at standard cosmology is that the conclusion that the universe is accelerating is model dependent. That’s fair enough.
Usually cosmologists are careful to say that we are studying “dark energy”, which is the name we give to whatever is causing the apparent acceleration of the expansion of the universe. (Often we drop the “apparent” in that sentence, but it is there by implication.)
“Dark energy” is a blanket term we use to cover many possibilities, including that vacuum energy causes acceleration, or that we need a new theory of gravity, or even that we’ve misinterpreted general relativity and need a more sophisticated model.
The key feature that is not in dispute is that there is some significant new physics apparent in this data. There is something that goes beyond what we know about how the universe works – something that needs to be explained.
So let’s look at what the new paper actually did. To do so, let’s use an analogy.
Margins of measurement
Imagine you’re driving a car down a 60km/h limit road. You measure your speed to be 55km/h, but your odometer has some uncertainty in it. You take this into account, and are 99% sure that you are travelling between 51km/h and 59km/h.
Now your friend comes along and analyses your data slightly differently. She measures your speed to be 57km/h. Yes, it is slightly different from your measurement, but still consistent because your odometer is not that accurate.
But now your friend says: “Ha! You were only marginally below the speed limit. There’s every possibility that you were speeding!”
In other words, the answer didn’t change significantly, but the interpretation given in the paper takes the extreme of the allowed region and says “maybe the extreme is true”.
For those who like detail, the three standard deviation limit of the supernova data is big enough (just) to include a non-accelerating universe. But that is only if there is essentially no matter in the universe and you ignore all other measurements (see figure, below).
Improving the analysis
This new paper is trying to do something laudable. It is trying to improve the statistical analysis of the data (for comments on their analysis see).
As we get more and more data and the uncertainty on our measurement shrinks, it becomes more and more important to take into account every last detail.
In fact, with the Dark Energy Survey we have three people working full-time on testing and improving the statistical analysis we use to compare supernova data to theory.
We recognise the importance of improved statistical analysis because we’re soon going to have about 3,000 supernovae with which to measure the acceleration far more precisely than the original discoveries, which only had 52 supernovae between them. The sample that this new paper re-analyses contains 740 supernovae.
One final note about the conclusions in the paper. The authors suggest that a non-accelerating universe is worth considering. That’s fine. But you and I, the Earth, the Milky Way and all the other galaxies should gravitationally attract each other.
So a universe that just expands at a constant rate is actually just as strange as one that accelerates. You still have to explain why the expansion doesn’t slow down due to the gravity of everything it contains.
So even if the non-acceleration claim made in this paper is true, the explanation still requires new physics, and the search for the “dark energy” that explains it is just as important.
Healthy scepticism is vital in research. There is still much debate over what is causing the acceleration, and whether it is just an apparent acceleration that arises because our understanding of gravity is not yet complete.
Indeed that is what we as professional cosmologists spend our entire careers investigating. What this new paper and all the earlier papers agree on is that there is something that needs to be explained.
The supernova data show something genuinely weird is going on. The solution might be acceleration, or a new theory of gravity. Whatever it is, we will continue to search for it.
Life exists in a myriad of wondrous forms, but if you break any organism down to its most basic parts, it’s all the same stuff: carbon atoms connected to hydrogen, oxygen, nitrogen and other elements. But how these fundamental substances are created in space has been a longstanding mystery.
Now, astronomers better understand how molecules form that are necessary for building other chemicals essential for life. Thanks to data from the European Space Agency’s Herschel Space Observatory, scientists have found that ultraviolet light from stars plays a key role in creating these molecules, rather than “shock” events that create turbulence, as was previously thought.
Scientists studied the ingredients of carbon chemistry in the Orion Nebula, the closest star-forming region to Earth that forms massive stars. They mapped the amount, temperature and motions of the carbon-hydrogen molecule (CH, or “methylidyne” to chemists), the carbon-hydrogen positive ion (CH+) and their parent: the carbon ion (C+). An ion is an atom or molecule with an imbalance of protons and electrons, resulting in a net charge.
“On Earth, the sun is the driving source of almost all the life on Earth. Now, we have learned that starlight drives the formation of chemicals that are precursors to chemicals that we need to make life,” said Patrick Morris, first author of the paper and researcher at the Infrared Processing and Analysis Center at Caltech in Pasadena.
In the early 1940s, CH and CH+ were two of the first three molecules ever discovered in interstellar space. In examining molecular clouds — assemblies of gas and dust — in Orion with Herschel, scientists were surprised to find that CH+ is emitting rather than absorbing light, meaning it is warmer than the background gas. The CH+ molecule needs a lot of energy to form and is extremely reactive, so it gets destroyed when it interacts with the background hydrogen in the cloud. Its warm temperature and high abundance are therefore quite mysterious.
Why, then, is there so much CH+ in molecular clouds such as the Orion Nebula? Many studies have tried to answer this question before, but their observations were limited because few background stars were available for studying. Herschel probes an area of the electromagnetic spectrum — the far infrared, associated with cold objects — that no other space telescope has reached before, so it could take into account the entire Orion Nebula instead of individual stars within. The instrument they used to obtain their data, HIFI, is also extremely sensitive to the motion of the gas clouds.
One of the leading theories about the origins of basic hydrocarbons has been that they formed in “shocks,” events that create a lot of turbulence, such as exploding supernovae or young stars spitting out material. Areas of molecular clouds that have a lot of turbulence generally create shocks. Like a large wave hitting a boat, shock waves cause vibrations in material they encounter. Those vibrations can knock electrons off atoms, making them ions, which are more likely to combine. But the new study found no correlation between these shocks and CH+ in the Orion Nebula.
Herschel data show that these CH+ molecules were more likely created by the ultraviolet emission of very young stars in the Orion Nebula, which, compared to the sun, are hotter, far more massive and emit much more ultraviolet light. When a molecule absorbs a photon of light, it becomes “excited” and has more energy to react with other particles. In the case of a hydrogen molecule, the hydrogen molecule vibrates, rotates faster or both when hit by an ultraviolet photon.
It has long been known that the Orion Nebula has a lot of hydrogen gas. When ultraviolet light from large stars heats up the surrounding hydrogen molecules, this creates prime conditions for forming hydrocarbons. As the interstellar hydrogen gets warmer, carbon ions that originally formed in stars begin to react with the molecular hydrogen, creating CH+. Eventually the CH+ captures an electron to form the neutral CH molecule.
“This is the initiation of the whole carbon chemistry,” said John Pearson, researcher at NASA’s Jet Propulsion Laboratory, Pasadena, California, and study co-author. “If you want to form anything more complicated, it goes through that pathway.”
Scientists combined Herschel data with models of molecular formation and found that ultraviolet light is the best explanation for how hydrocarbons form in the Orion Nebula.
The findings have implications for the formation of basic hydrocarbons in other galaxies as well. It is known that other galaxies have shocks, but dense regions in which ultraviolet light dominates heating and chemistry may play the key role in creating fundamental hydrocarbon molecules there, too.
“It’s still a mystery how certain molecules get excited in the cores of galaxies,” Pearson said. “Our study is a clue that ultraviolet light from massive stars could be driving the excitation of molecules there, too.”
Herschel is a European Space Agency mission, with science instruments provided by consortia of European institutes and with important participation by NASA. While the observatory stopped making science observations in April 2013, after running out of liquid coolant as expected, scientists continue to analyze its data. NASA’s Herschel Project Office is based at NASA’s Jet Propulsion Laboratory, Pasadena, California. JPL contributed mission-enabling technology for two of Herschel’s three science instruments. The NASA Herschel Science Center, part of IPAC, supports the U.S. astronomical community. Caltech manages JPL for NASA.
Originally published at NASA
Dark matter is a mysterious substance composing most of the material universe, now widely thought to be some form of massive exotic particle. An intriguing alternative view is that dark matter is made of black holes formed during the first second of our universe’s existence, known as primordial black holes. Now a scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, suggests that this interpretation aligns with our knowledge of cosmic infrared and X-ray background glows and may explain the unexpectedly high masses of merging black holes detected last year.
“This study is an effort to bring together a broad set of ideas and observations to test how well they fit, and the fit is surprisingly good,” said Alexander Kashlinsky, an astrophysicist at NASA Goddard. “If this is correct, then all galaxies, including our own, are embedded within a vast sphere of black holes each about 30 times the sun’s mass.”
In 2005, Kashlinsky led a team of astronomers using NASA’s Spitzer Space Telescope to explore the background glow of infrared light in one part of the sky. The researchers reported excessive patchiness in the glow and concluded it was likely caused by the aggregate light of the first sources to illuminate the universe more than 13 billion years ago. Follow-up studies confirmed that this cosmic infrared background (CIB) showed similar unexpected structure in other parts of the sky.
In 2013, another study compared how the cosmic X-ray background (CXB) detected by NASA’s Chandra X-ray Observatory compared to the CIB in the same area of the sky. The first stars emitted mainly optical and ultraviolet light, which today is stretched into the infrared by the expansion of space, so they should not contribute significantly to the CXB.
Yet the irregular glow of low-energy X-rays in the CXB matched the patchiness of the CIB quite well. The only object we know of that can be sufficiently luminous across this wide an energy range is a black hole. The research team concluded that primordial black holes must have been abundant among the earliest stars, making up at least about one out of every five of the sources contributing to the CIB.
The nature of dark matter remains one of the most important unresolved issues in astrophysics. Scientists currently favor theoretical models that explain dark matter as an exotic massive particle, but so far searches have failed to turn up evidence these hypothetical particles actually exist. NASA is currently investigating this issue as part of its Alpha Magnetic Spectrometer and Fermi Gamma-ray Space Telescope missions.
“These studies are providing increasingly sensitive results, slowly shrinking the box of parameters where dark matter particles can hide,” Kashlinsky said. “The failure to find them has led to renewed interest in studying how well primordial black holes — black holes formed in the universe’s first fraction of a second — could work as dark matter.”
Physicists have outlined several ways in which the hot, rapidly expanding universe could produce primordial black holes in the first thousandths of a second after the Big Bang. The older the universe is when these mechanisms take hold, the larger the black holes can be. And because the window for creating them lasts only a tiny fraction of the first second, scientists expect primordial black holes would exhibit a narrow range of masses.
On Sept. 14, gravitational waves produced by a pair of merging black holes 1.3 billion light-years away were captured by the Laser Interferometer Gravitational-Wave Observatory (LIGO) facilities in Hanford, Washington, and Livingston, Louisiana. This event marked the first-ever detection of gravitational waves as well as the first direct detection of black holes. The signal provided LIGO scientists with information about the masses of the individual black holes, which were 29 and 36 times the sun’s mass, plus or minus about four solar masses. These values were both unexpectedly large and surprisingly similar.
“Depending on the mechanism at work, primordial black holes could have properties very similar to what LIGO detected,” Kashlinsky explained. “If we assume this is the case, that LIGO caught a merger of black holes formed in the early universe, we can look at the consequences this has on our understanding of how the cosmos ultimately evolved.”
In his new paper, published May 24 in The Astrophysical Journal Letters, Kashlinsky analyzes what might have happened if dark matter consisted of a population of black holes similar to those detected by LIGO. The black holes distort the distribution of mass in the early universe, adding a small fluctuation that has consequences hundreds of millions of years later, when the first stars begin to form.
For much of the universe’s first 500 million years, normal matter remained too hot to coalesce into the first stars. Dark matter was unaffected by the high temperature because, whatever its nature, it primarily interacts through gravity. Aggregating by mutual attraction, dark matter first collapsed into clumps called minihaloes, which provided a gravitational seed enabling normal matter to accumulate. Hot gas collapsed toward the minihaloes, resulting in pockets of gas dense enough to further collapse on their own into the first stars. Kashlinsky shows that if black holes play the part of dark matter, this process occurs more rapidly and easily produces the lumpiness of the CIB detected in Spitzer data even if only a small fraction of minihaloes manage to produce stars.
As cosmic gas fell into the minihaloes, their constituent black holes would naturally capture some of it too. Matter falling toward a black hole heats up and ultimately produces X-rays. Together, infrared light from the first stars and X-rays from gas falling into dark matter black holes can account for the observed agreement between the patchiness of the CIB and the CXB.
Occasionally, some primordial black holes will pass close enough to be gravitationally captured into binary systems. The black holes in each of these binaries will, over eons, emit gravitational radiation, lose orbital energy and spiral inward, ultimately merging into a larger black hole like the event LIGO observed.
“Future LIGO observing runs will tell us much more about the universe’s population of black holes, and it won’t be long before we’ll know if the scenario I outline is either supported or ruled out,” Kashlinsky said.
Kashlinsky leads science team centered at Goddard that is participating in the European Space Agency’s Euclid mission, which is currently scheduled to launch in 2020. The project, named LIBRAE, will enable the observatory to probe source populations in the CIB with high precision and determine what portion was produced by black holes.
Originally published at NASA
An international team of scientists believe that new data supports the idea that our universe could be a hologram.
A study published in the Physical Review Letters seems to indicate that the argument for a holographic universe is just a strong as that of our standard cosmological model.
While it’s an astonishing claim, it doesn’t mean that our entire reality is a fabrication. Rather the holographic universe argument maintains that we need to rethink the way we envision our universe; specifically being that the holographic principle states that properties of three-dimensional universe’ could be encoded on a two dimensional surface.
“Imagine that everything you see, feel and hear in three dimensions (and your perception of time) in fact emanates from a flat two-dimensional field.The idea is similar to that of ordinary holograms where a three-dimensional image is encoded in a two-dimensional surface, such as in the hologram on a credit card. However, this time, the entire universe is encoded.”
– Professor Kostas Skenderis, University of Southampton
Research was tested against observations of the early universe made by the ESA’s Planck observatory. Some of the findings for the holographic theory universe did not add up, but for the most part the models satisfied the speculations.
“The structure of these deviations encodes the physics of the very early universe,” says Skenderis. “So then the question is, if you have a theory for the very early universe, can you predict the structure of the small deviations?”
“When we go into this concept of holography, it’s a new way of thinking about things. Even the scientists who worked on this for the past 20 years don’t have the right tools or the right language to describe what’s going on. It’s a new paradigm for a physical reality.”
“I would argue this is the simplest theory of the early universe. And so far, this is as simple as it gets. And it could help explain everything we see,” says Niayesh Afshordi, lead author of the paper. This idea, contrasted with Occam’s razor – a scientific and philosophic principle that maintains the simplest explanation is usually the correct one – paints a thought provoking picture. We may very well be living in a hologram.
High above the surface, Earth’s magnetic field constantly deflects incoming supersonic particles from the sun. These particles are disturbed in regions just outside of Earth’s magnetic field – and some are reflected into a turbulent region called the foreshock. New observations from NASA’s THEMIS – short for Time History of Events and Macroscale Interactions during Substorms – mission show that this turbulent region can accelerate electrons up to speeds approaching the speed of light. Such extremely fast particles have been observed in near-Earth space and many other places in the universe, but the mechanisms that accelerate them have not yet been concretely understood.
The new results provide the first steps towards an answer, while opening up more questions. The research finds electrons can be accelerated to extremely high speeds in a near-Earth region farther from Earth than previously thought possible – leading to new inquiries about what causes the acceleration. These findings may change the accepted theories on how electrons can be accelerated not only in shocks near Earth, but also throughout the universe. Having a better understanding of how particles are energized will help scientists and engineers better equip spacecraft and astronauts to deal with these particles, which can cause equipment to malfunction and affect space travelers.
“This affects pretty much every field that deals with high-energy particles, from studies of cosmic rays to solar flares and coronal mass ejections, which have the potential to damage satellites and affect astronauts on expeditions to Mars,” said Lynn Wilson, lead author of the paper on these results at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The results, published in Physical Review Letters, on Nov. 14, 2016, describe how such particles may get accelerated in specific regions just beyond Earth’s magnetic field. Typically, a particle streaming toward Earth first encounters a boundary region known as the bow shock, which forms a protective barrier between the solar wind, the continuous and varying stream of charged particles flowing from the sun, and Earth. The magnetic field in the bow shock slows the particles, causing most to be deflected away from Earth, though some are reflected back towards the sun. These reflected particles form a region of electrons and ions called the foreshock region.
Some of those particles in the foreshock region are highly energetic, fast moving electrons and ions. Historically, scientists have thought one way these particles get to such high energies is by bouncing back and forth across the bow shock, gaining a little extra energy from each collision. However, the new observations suggest the particles can also gain energy through electromagnetic activity in the foreshock region itself.
The observations that led to this discovery were taken from one of the THEMIS – short for Time History of Events and Macroscale Interactions during Substorms – mission satellites. The five THEMIS satellites circled Earth to study how the planet’s magnetosphere captured and released solar wind energy, in order to understand what initiates the geomagnetic substorms that cause aurora. The THEMIS orbits took the spacecraft across the foreshock boundary regions. The primary THEMIS mission concluded successfully in 2010 and now two of the satellites collect data in orbit around the moon.
Operating between the sun and Earth, the spacecraft found electrons accelerated to extremely high energies. The accelerated observations lasted less than a minute, but were much higher than the average energy of particles in the region, and much higher than can be explained by collisions alone. Simultaneous observations from the additional Heliophysics spacecraft, Wind and STEREO, showed no solar radio bursts or interplanetary shocks, so the high-energy electrons did not originate from solar activity.
“This is a puzzling case because we’re seeing energetic electrons where we don’t think they should be, and no model fits them,” said David Sibeck, co-author and THEMIS project scientist at NASA Goddard. “There is a gap in our knowledge, something basic is missing.”
The electrons also could not have originated from the bow shock, as had been previously thought. If the electrons were accelerated in the bow shock, they would have a preferred movement direction and location – in line with the magnetic field and moving away from the bow shock in a small, specific region. However, the observed electrons were moving in all directions, not just along magnetic field lines. Additionally, the bow shock can only produce energies at roughly one tenth of the observed electrons’ energies. Instead, the cause of the electrons’ acceleration was found to be within the foreshock region itself.
“It seems to suggest that incredibly small scale things are doing this because the large scale stuff can’t explain it,” Wilson said.
High-energy particles have been observed in the foreshock region for more than 50 years, but until now, no one had seen the high-energy electrons originate from within the foreshock region. This is partially due to the short timescale on which the electrons are accelerated, as previous observations had averaged over several minutes, which may have hidden any event. THEMIS gathers observations much more quickly, making it uniquely able to see the particles.
Next, the researchers intend to gather more observations from THEMIS to determine the specific mechanism behind the electrons’ acceleration.
Originally published at NASA
CAPE CANAVERAL, Fla. (Reuters) – The universe is expanding faster than previously believed, a surprising discovery that could test part of Albert Einstein’s theory of relativity, a pillar of cosmology that has withstood challenges for a century.
The discovery that the universe is expanding 5 percent to 9 percent faster than predicted, announced in joint news releases by NASA and the European Space Agency, also stirs hypotheses about what fills the 95 percent of the cosmos that emits no light and no radiation, scientists said on Thursday.
“Maybe the universe is tricking us,” said Alex Filippenko, a University of California, Berkeley astronomer and co-author of an upcoming paper about the discovery.
The universe’s rate of expansion does not match predictions based on measurements of the remnant radiation left over from the Big Bang explosion that gave rise to the known universe 13.8 billion years ago.
One possibility for the discrepancy is that the universe has unknown subatomic particles, similar to neutrinos, that travel nearly as fast as the speed of light, which is about 186,000 miles (300,000 km) per second.
Another idea is that so-called “dark energy,” a mysterious, anti-gravity force discovered in 1998, may be shoving galaxies away from one another more powerfully than originally estimated.
“This may be an important clue to understanding those parts of the universe that make up 95 percent of everything and that don’t emit light, such as dark energy, dark matter and dark radiation,” physicist and lead author Adam Riess, with the Space Telescope Science Institute in Baltimore, Maryland, said in a statement.
Riess shared the 2011 Nobel Prize in Physics for the discovery that the expansion of the universe was speeding up.
The speedier universe also raises the possibility that Einstein’s general theory of relativity, which serves as the mathematical scaffolding for calculating how the basic building blocks of matter interact, is slightly wrong, NASA said.
Riess and colleagues made their discovery by building a better cosmic yardstick to calculate distances. They used the Hubble Space Telescope to measure a particular type of star, known as Cepheid variables, in 19 galaxies beyond our own Milky Way galaxy.
How fast these stars pulse is directly related to how bright they are, which in turn can be used to calculate their distances, much like a 100-watt light bulb appears dimmer the farther away it is.
The research will be published in an upcoming edition of The Astrophysical Journal.
(Reporting by Irene Klotz; editing by Daniel Trotta and Tom Brown)