Category Archives: Black Hole

The mysterious dark energy that speeds the universe’s rate of expansion

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The nature of dark energy is one of the most important unsolved problems in all of science. But what, exactly, is dark energy, and why do we even believe that it exists?

What goes up must come down… right?
Ball image via www.shutterstock.com.

Step back a minute and consider a more familiar experience: what happens when you toss a ball straight up into the air? It gradually slows down as gravity tugs on it, finally stopping in mid-air and falling back to the ground. Of course, if you threw the ball hard enough (about 25,000 miles per hour) it would actually escape from the Earth entirely and shoot into space, never to return. But even in that case, gravity would continue to pull feebly on the ball, slowing its speed as it escaped the clutches of the Earth.

But now imagine something completely different. Suppose that you tossed a ball into the air, and instead of being attracted back to the ground, the ball was repelled by the Earth and blasted faster and faster into the sky. This would be an astonishing event, but it’s exactly what astronomers have observed happening to the entire universe!

This illustration shows abstracted ‘slices’ of space at different points in time as the universe expands.
Ævar Arnfjörð Bjarmason, CC BY-SA

Scientists have known for almost a century that the universe is expanding, with all of the galaxies flying apart from each other. And until recently, scientists believed that there were only two possible options for the universe in the future. It could expand forever (like the ball that you tossed upward at 25,000 miles an hour), but with the expansion slowing down as gravity pulled all of the galaxies toward each other. Or gravity might win out in the end and bring the expansion of the universe to a halt, finally collapsing it back down in a “big crunch,” just like your ball plunging back to the ground.

So imagine scientists’ surprise when two different teams of astronomers discovered, back in 1998, that neither of these behaviors was correct. These astronomers were measuring how fast the universe was expanding when it was much younger than today. But how could they do this without building a time machine?

Luckily, a telescope is a time machine. When you look up at the stars at night, you aren’t seeing what they look like today – you’re seeing light that left the stars a long time ago – often many hundreds of years. By looking at distant supernovae, which are tremendously bright exploding stars, astronomers can look back hundreds of millions of years. They can then measure the expansion rate back then by comparing the distance to these far-off supernovae with the speed at which they are flying away from us. And by comparing how fast the universe was expanding hundreds of millions of years ago to its rate of expansion today, these astronomers discovered that the expansion is actually speeding up instead of slowing down as everyone had expected.

What pushes galaxies like these in the Hubble deep field apart?
NASA and A. Riess (STScI), CC BY

Instead of pulling the galaxies in the universe together, gravity seems to be driving them apart. But how can gravity be repulsive, when our everyday experience shows that it’s attractive? Einstein’s theory of gravity in fact predicts that gravity can repel as well as attract, but only under very special circumstances.

Repulsive gravity requires a new form of energy, dubbed “dark energy,” with very weird properties. Unlike ordinary matter, dark energy has negative pressure, and it’s this negative pressure that makes gravity repulsive. (For ordinary matter, gravity is always attractive). Dark energy appears to be smoothly smeared out through the entire universe, and it interacts with ordinary matter only through the action of gravity, making it nearly impossible to test in the laboratory.

Scientists used to think that the expansion of the universe was described by the yellow, green, or blue curves. But surprise, it’s actually the red curve instead.

The simplest form of dark energy goes by two different names: a cosmological constant or vacuum energy. Vacuum energy has another strange property. Imagine a box that expands as the universe expands. The amount of matter in the box stays the same as the box expands, but the volume of the box goes up, so the density of matter in the box goes down. In fact, the density of everything goes down as the universe expands. Except for vacuum energy – its density stays exactly the same. (Yes, that’s as bizarre as it sounds. It’s like stretching a string of taffy and discovering that it never gets any thinner).

Astronomers continue to probe the skies, looking for finer details that can build on what we suspect about dark energy.
Reidar Hahn, CC BY

Since dark energy can’t be isolated or probed in the laboratory, how can we hope to understand exactly what it’s made of? Different theories for dark energy predict small differences in the way that the expansion of the universe changes with time, so our best hope of probing dark energy seems to come from ever more accurate measurements of the acceleration of the universe, building on that first discovery 17 years ago. Different groups of scientists are currently undertaking a wide range of these measurements. For example, the Dark Energy Survey is mapping out the distribution of galaxies in the universe to help resolve this puzzle.

Could Einstein’s theory need work?
Sophie Delar

There is one other possibility: maybe scientists have been barking up the wrong tree. Maybe there is no dark energy, and our measurements actually mean that Einstein’s theory of gravity is wrong and needs to be fixed. This would be a daunting undertaking, since Einstein’s theory works exceptionally well when we test it in the solar system. (Let’s face it, Einstein really knew what he was doing). So far, no one has produced a convincing improvement on Einstein’s theory that predicts the correct expansion for the universe and yet agrees with Einstein’s theory inside the solar system. I’ll leave that as a homework problem for the reader.

The Conversation

This article was originally published on The Conversation.
Read the original article.

Your Interpretation of Quantum Physics is Probably Wrong

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Quantum theory can be misinterpreted to support false claims.

pseudoscience6102011uj

There is legit science to quantum theory but misinterpretations justify an assortment of pseudoscience. Let’s examine why.

Quantum science isn’t a young science anymore. This year, 2015, the term “quantum”, as it relates to quantum physics, turns 113 years old. The term as we know it first appeared “in a 1902 article on the photoelectric effect by Philipp Lenard, who credited Hermann von Helmholtz for using the word in reference to electricity”(Wikipedia). During it’s first century of life attempts to understand quantum particle behavior have lead to a bunch of discoveries. Quantum physics has furthered understanding of key physical aspects of the universe. That complex understanding has been used to develop new technologies.

Quantum physics is enigmatic in that it pushes the limits of conceptualization itself, leaving it seemingly open to interpretation. While it is has been used to predict findings and improve human understanding, It’s also been used by charlatans who have a shaky-at-best understanding of science. Quantum physics has been misappropriated to support a bunch of downright unscientific ideas.

It’s easy to see why it can be misunderstood by well-intentioned people and foisted upon an unsuspecting public by new age hacks. The best minds in academia don’t always agree on secondary implications of quantum physics. No one has squared quantum theory with the theory of relativity,  for example.

Most people are not smart enough to parse all the available research on quantum physics. The public’s research skills are notoriously flawed on any subject. The internet is rife with misinformation pitting researchers against their own lack of critical thinking skills. Anti-science and pseudoscience alike get a surprising amount of traction online, with Americans believing in a wide variety of superstitions and erroneous claims.

In addition to the public simply misinterpreting or misunderstanding the science, there is money to be made in taking advantage of gullible people. Here are some false claims that have erroneously used quantum theory as supporting evidence:

Many Interacting Worlds

The internet loves this one. Contemporary multiple universe theorMultiverse1ies are philosophy, not science, but that didn’t stop Australian physicists Howard Wiseman and Dr. Michael Hall from collaborating with  UC Davis mathematician Dr. Dirk-Andre Deckert to publish the “many interacting worlds” theory as legit science in the otherwise respectable journal, Physical Review X. This is the latest in a train of thought that forgoes scientific reliance on evidence and simply supposes the existence of other universes, taking it a step further by insisting we live in an actual multiverse, with alternate universes constantly influence each other. Um, that’s awesome but it’s not science. You can read their interpretation of reality for yourself.

Deepak Chopra

Deepak Chopra is a celebrated new age guru whose views on the human condition and spirituality are respected by large numbers of the uneducated. By misinterpreting quantum physics he has made a career of stitching together a nonsensical belief system from disjointed but seemingly actual science. Chopra’s false claims can seem very true when first investigated but has explained key details that Chopra nonetheless considers mysterious.

The Secret™

‘The Power’ and ‘The Secret’ are best-selling books that claim science supports what can be interpreted as an almost maniacal selfishness. The New York Times once described the books as “larded with references to magnets, energy and quantum mechanics.” the secret

The Secret’s author,  Rhonda Byrne, uses confusing metaphysics not rooted in any known or current study of consciousness by borrowing heavily from important-sounding terminology found in psychology and neuroscience.  Byrne’s  pseudoscientific jargon is surprisingly readable and comforting but that doesn’t make the science behind it any less bogus.

Scientology

L._Ron_Hubbard_in_1950

There isn’t anything in quantum physics implying a solipsism or subjective experience of reality but that doesn’t stop Scientology from pretending we each have our own “reality” – and yours is broken.

Then there is the oft-headlining, almost post modern psuedoscientific masterpiece of utter bullshit: Scientology.

Scientology uses this same type of claim to control it’s cult following. Scientology relies on a re-fabrication of the conventional vocabulary normal, English-speaking people use. The religion drastically redefined the word reality. L.R. Hubbard called reality the “agreement.” Scientologists believe the universe is a construct of the spiritual beings living within it. The real world we all share is, to them, a product of consensus. Scientology describes, for example, mentally ill people as those who no longer accept an “agreed upon apparency” that has been “mocked up” by we spiritual beings, to use their reinvented terminology. Scientologists misuse of the word reality to ask humans, “what’s your reality?” There isn’t anything in quantum physics implying a solipsism or subjective experience of reality but that doesn’t stop Scientology.

In conclusion…

The struggle to connect quantum physics to spirituality is a humorous metaphor for subjectivity itself.

If you find yourself curious to learn more about quantum theory you should read up and keep and open mind, no doubt. The nature of a mystery is that it hasn’t been explained. Whatever evidence that might be able to help humanity understand the way reality is constructed is not going to come from religion or superstition, it will come from science. Regardless of the claims to the contrary, quantum theory only points out a gap in understanding and doesn’t explain anything about existence, consciousness or subjective reality.
Jonathan Howard
Jonathan is a freelance writer living in Brooklyn, NY

Young star theory forged from near miss with giant black hole

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Observations of the dusty cloud G2 as it approaches and then swings around the supermassive black hole at the centre of the Milky Way. ESO/A. Eckart, CC BY

It was billed as the biggest event in the galactic centre since we discovered that the Milky Way harboured a supermassive black hole. The G2 gas cloud, discovered in 2011, was found to be heading directly towards the black hole.

Given the estimated mass – a few Earth masses of gas – there was no way it could possibly survive the passage intact.

Immediately theorists set to work computing the likely shredding of the cloud as it reached it’s closest approach. Most simulations predicted a spectacular breakup, leading to some gas being “eaten” by the black hole.

Some of the theoretical predictions of G2’s breakup

Since accretion onto black holes is one of the most energetic processes in the universe, everyone got excited about the possible “waking” of the sleeping giant at the galactic centre. The “burps” from the last time the Milky Way’s black hole started feasting are now as big as the galaxy itself.

The Fermi Bubbles.
NASA/DOE/Fermi LAT/D. Finkbeiner et al.

Something strange

The G2 story started in 1992 when the cluster of S (for Strange) stars were discovered orbiting the supermassive black hole.

Since then several groups of astronomers have been carefully tracking the motion of these stars, making for some amazing time-lapse movies of them whipping around in space, orbiting around an invisible “something”.

Motion of stars around the Galactic Centre. These images/animations were created by Prof Andrea Ghez and her research team at UCLA and are from data sets obtained with the W M Keck Telescopes.

One of these stars in particular, S2, orbits with a period of just 16 years in an ellipse with a closest approach of 120 AU (AU = Earth-Sun distance), indicating that it is orbiting a body with mass more than 3.5 million times the mass of the Sun but which is completely invisible at optical wavelengths! (This is our best argument yet that actual black holes really do exist).

Given the amazing results that have been pouring from the research groups tracking the S stars, the subsequent discovery in 2011 of the G2 cloud heading right for the black hole was the icing on the cake.

Collision course

Closest approach was billed for the end of 2014. A vast array of the world’s most expensive telescopes were excitedly pointed towards the galactic centre to witness the fireworks.

And, like a cancelled New Year’s Eve event in the pouring rain, nothing happened and everyone went home soggy and disappointed.

Theorists hurriedly revised their calculations and heated debate ensued between the “it’s a star hidden by dust” and “it’s a gas cloud” camps.

The key point being that a cloud consisting of just gas has very little gravity to hold itself together against the tidal forces of the black hole, whereas a cloud with an embedded star could easily hold together and come out the other side relatively unscathed.

Nevertheless the observers were adamant that there was no star to be seen, and that a gas cloud it must be – there were even signs of the gas cloud “stretching” as it went through it’s closest approach.

So what is it?

With the recent results from ESO published this week, the G2 saga rolls on. The fireworks are still off. Even the supposed “stretching” has not withstood further scrutiny.

This means the gas cloud theory is becoming less and less viable, and the only conclusion is that, whatever G2 is, in order to survive the passage like it has it must be held together by the gravity of something more than a few Earth masses of gas.

In one sense this is reassuring, as the gas cloud theory always had holes in it – for example the cloud would have had to appear right at the time it was first observed.

The idea that it is a young star that somehow got knocked towards the galactic centre is much more consistent with what we already know about the other stars in the galactic centre and how they got there.

We’re disappointed about the lack of fireworks – they’re postponed but not officially cancelled yet – but the attention and excitement focused on the galactic centre is certainly not misplaced – it’s a unique laboratory for understanding the galaxy we call home.

The Conversation

This article was originally published on The Conversation.
Read the original article.

How the Large Hadron Collider Might Disprove the Big Bang

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First proposed in 1927 by Belgian physicist Georges Lemaitre as the “Hypothesis of the Primeval Atom,” the Big Bang Theory (mostly associated with the sitcom but popularized in movies since Disney’s Fantasia), remains the predominant explanation for the origin of how our universe got to be the way it is today – starting from a particle smaller than an atom that inflated some 13.8 billion years ago.

It wasn’t always, though. For another forty years, despite the increasing evidence of an ever-expanding universe – galaxies drifting apart from each other, of varying ages and shapes; an abundance of light chemicals like hydrogen (about 75% of the universe) and helium; and the presence of cosmic microwaves, radiation that transitioned from visible light (some of the leftover radiation can be seen in the static given off by analog TV signals) – many astronomers clung to a steady-state model of the universe that gradually acquires matter. Astronomer Fred Hoyle even derisively referred to it once as the “Big Bang” and the name stuck.

So was there anything before it? We don’t know. Then again, there also was no time or space before the Big Bang event either. Some evidence has been proposed that the universe has always existed, eons before the Big Bang set everything in its current state. The overwhelming majority of the universe is invisible, and sometimes the question is raised of whether the universe really is singular – or is it one of many? Nothing is sacred as the Large Hadron Collider (LHC) of the European Organization for Nuclear Research (CERN) is unleashed in Geneva this week.

http://www.telegraph.co.uk/news/science/large-hadron-collider/11489442/Big-Bang-theory-could-be-debunked-by-Large-Hadron-Collider.html

If the Large Hadron Collider finds miniature black holes, it may provide the evidence we need that parallel universes in fact do exist, and potentially that the Big Bang did not occur as cosmologists once envisioned. Already, the particle accelerator, currently the largest in the world, discovered the Higgs boson, known as the God Particle, which physicists suspect is what provides other particles with mass.

If these holes give off a specific wavelength of energy, they could be further testimony for a rather controversial theory known as ‘rainbow gravity,’ proposing that our universe may reach an indefinite distance back in time, without a singular point of origin, and no cosmic inflation event necessary to start the beginning of matter as we know it.

The theory is reconciled from Einstein’s theory of general relativity and suggests that varying wavelengths of light affect gravity in different ways. Were you to look backwards in time, the universe is more dense than in the present. Although it comes close to an extreme and infinite density, it never quite gets there. Consequently, its concept of the early universe is a bit different than the picture we have now.

While this all sounds very surreal – Earth would scarcely feel the impact of rainbow gravity. Black holes, however, would pick up on it considerably – increments that could be sizable and measurable, and easily within the range of the LHC.

“We have calculated the energy at which we expect to detect these mini black holes in gravity’s rainbow [a new theory]. If we do detect mini black holes at this energy, then we will know that both gravity’s rainbow and extra dimensions are correct,” said CERN researcher Dr. Mir Faizal to Phys.org.

This week will be the LHC’s second run, after being shut down for new installations at the beginning of 2013. It will be fully operational by Wednesday with its beams opening full circle.

When the 27 km accelerator is active it will begin hammering together protons at a rate nearly twice the energy needed to discover Higgs boson.

Rolf Heuer, Director General of CERN, hailed the switch-on as unprecedented, ‘a new era for physics’ that could shed some light on those not so visible forces in the universe: dark matter, dark energy and super-symmetry.

“I want to see the first light in the dark universe. If that happens, then nature is kind to me,” said Heuer.

Then there is that sci-fi fantasy that almost seems within reach of the LHC – a bridge between two worlds, or rather, two universes – a probability that another parallel dimension could bleed into our own.

Do the physicists have an explanation for this yet?

“Just as many parallel sheets of paper, which are two dimensional objects [breadth and length] can exist in a third dimension [height], parallel universes can also exist in higher dimensions,” added Dr Faizal.

“We predict that gravity can leak into extra dimensions, and if it does, then miniature black holes can be produced at the LHC.

“Normally, when people think of the multiverse, they think of the many-worlds interpretation of quantum mechanics, where every possibility is actualised. This cannot be tested and so it is philosophy and not science.

“This is not what we mean by parallel universes. What we mean is real universes in extra dimensions.

“As gravity can flow out of our universe into the extra dimensions, such a model can be tested by the detection of mini black holes at the LHC.”

Since its two-year hibernation, the new and improved LHC has quite a few things to brag about before being fired up for its next run: newer, more powerful magnets, superior cryogenics (you read that right – the LHC is in fact the coldest place on Earth, with an epic cooling system that can keep noble gases like krypton in liquid form), higher voltage and even higher energy beams that mean an acceleration nearly twice what it made on its first run.

Frances Saunders, president of the IOP, said, “This has been a massive effort by all the scientists and engineers at CERN to upgrade the LHC and its detectors and get it ready to operate at almost double the collision energies of the first run.

“As well as allowing greater study of the Higgs boson there is much anticipation amongst the physics community as to what else may be found at these higher energies, testing our theories and understanding of concepts such as supersymmetry and potentially giving greater insight into the 95 per cent of the universe that is composed of dark matter and dark energy.”
James Sullivan
James Sullivan is the assistant editor of Brain World Magazine and a contributor to Truth Is Cool and OMNI Reboot. He can usually be found on TVTropes or RationalWiki when not exploiting life and science stories for another blog article.