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Ethan Siegel
Works at NASA's The Space Place
Attended University of Florida College of Liberal Arts and Sciences
Lived in Bronx, New York
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Ethan Siegel

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"Yet in all of them, a very interesting and unexpected property shows itself: there’s a relationship between the observed gravitational acceleration and the distribution of the normal (baryonic, or protons, neutrons and electrons) matter alone. In other words, if you measure how quickly the galaxies rotate, it seems to depend — within a reasonable set of errors — only on the presence of the normal matter. "

Dark matter is a hugely successful theory for explaining a whole slew of observations about the Universe. Just by adding this one ingredient to the mix, we can successfully simulate and reproduce the large-scale structure, CMB fluctuations, galaxy clustering and cluster collision properties observed in our Universe. Without dark matter, there's no other way known to make the Universe work in line with what we see. And yet, if you go down to the small scales of individual galaxies, dark matter predicts a dark matter halo of a specific profile with specific rotation properties. When we look at the actual galaxies, those rotation properties don't match! Even worse, they appear to be correlated solely with the normal matter content of the galaxies, and have no dependence on whether the galaxy is rich-or-poor in dark matter.

Could this observation be the demise of dark matter? No matter what, it's a challenge that even the most robust theory must face!
There's some incredible evidence for the Universe's most elusive substance, but this one observation poses a challenge like no other.
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Dark matter,,,,,, matter's
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“Hubble can only expose visible and near-infrared light; it can only see stars. But there’s much more to the Universe. Most of the normal matter in the Universe is present in the forms of plasma and neutral gas, not stars. Although Hubble cannot see this gas, it emits light nonetheless, just at longer (radio) wavelengths.”

The Hubble Ultra Deep Field and its successor images represent humanity’s deepest views of the stars in our Universe. But there’s more to the Universe than just stars; even the normal matter in the Universe is more commonly present in the forms of gas and plasma than in stars. Hubble can never image those so far away, since their wavelengths are too long. But the Atacama Large Millimetre/submillimetre Array (ALMA) can see exactly that. By tuning ALMA so that it was very sensitive to a particular emission feature at high redshift – a carbon monoxide (CO) emission line – astronomers were able to construct a radio deep field image at the same location where the Hubble Ultra Deep Field was. What they revealed was a composite image of the stars and gas, shown together for the first time, finding that the Universe’s neutral gas is in great abundance only at the highest of redshifts.

Find out what this teaches us about the distant Universe over on today’s Mostly Mute Monday!
The Hubble Space Telescope provides the deepest views of the distant Universe, but it can't see everything. Thanks to ALMA, we've just seen a whole lot more.
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+Manmohan Haralalka From Wikipedia:

"According to the theory of cosmic inflation and its founder, Alan Guth, if it is assumed that inflation began about 10−37 seconds after the Big Bang, then with the plausible assumption that the size of the Universe before the inflation occurred was approximately equal to the speed of light times its age, that would suggest that at present the entire universe's size is at least 3x10 23 times larger than the size of the observable universe."

That means that the visible universe is much, much smaller than 6% of the whole.
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“See ourselves as we were in the past. You can’t use warp drive to travel back in time, but if you can outrace the light that the Earth, Sun or Milky Way emitted so long ago, you can then “catch” it with the proper tools. Warp yourself to 65 million light years away, and with a good enough telescope, you can see the asteroid that wiped out the dinosaurs. Warp to 12,000 light years away, and you can see the end of the last ice age. Warp to 53 light years away and watch, for yourself, who really shot JFK. Or go back to 4.5 billion light years away, and watch our Solar System as it’s first being born. Warp drive, coupled with a powerful enough telescope, would suddenly become the ultimate forensic tool.”

When Star Trek debuted 50 years ago, we didn’t know that there would be regions of the Universe that were forever inaccessible to humanity, nor that there would be galaxies permanently unreachable to us, even if we managed to develop near-light-speed travel technology. Yet thanks to the existence and dominance of dark energy today, that’s exactly the case. The only workaround, it appears, would be to develop faster-than-light travel. But with the physical possibility of the Alcubierre solution to General Relativity, which would enable warp drive, this might actually render these distant, unreachable regions someday traversable. Not only that, but a whole slew of other “physical impossibilities” would suddenly become possible, enabling us to perform acts that physics without warp travel would simply never allow.

There’s a whole slew of fun physics to explore if negative mass/energy is real, and this week’s Ask Ethan goes after the biggest stakes of all!
Going faster than the speed of light would enable us to travel the stars in a single human lifetime. But other 'impossible' consequences are even wilder!
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Impossible physics? More impossible than a self-aware, self-honest geek?
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Ethan Siegel

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“And yet, it’s philosophically dissatisfying. This “physical nothing” sounds very much like something, doesn’t it? When we want to talk about nothing, our conceptions take us outside of space and before the Universe began, yet does that even make sense? How can you talk about “outside” when you don’t have space? How can you talk about “before” anything if you don’t have time?

And yet, whatever “nothingness” truly is, it contains the entire Universe.”

If you think about the Universe, what it is today, what it contains and what makes it up, it very much is “something” by any way you’ll attempt to define it. Yet every “something” we know of has an origin, and the only ultimate origin for the first “something” is that it must have come from nothing. Yet what do we mean, as physicists, when we talk about nothing? Do we mean empty space; do we mean the quantum vacuum; do we mean the nothingness of our Universe or the Multiverse; do we mean the state from which space and time and the laws of physics first arose? Physicists and philosophers don’t necessarily have a good answer to this, yet that doesn’t mean we don’t have intelligent things about the different types of nothingness to talk about!

Come get the best definitions that we know of, and a few different, interesting perspectives on the physics of nothing.
Did the entire Universe come from nothing? And if so, how close to what we idealize as "nothingness" is it really?
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"-Throw out all numbers !" Well, I don't have a problem throwing out imaginary things thought of by human beings ;). As far as I can tell, numbers simply are human imaginations. 
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Ethan Siegel

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"Yes, there are questions we’re still working on, such as how the matter/antimatter asymmetry came to be, how the Big Bang got set up and started, and how, exactly, the Universe will meet its ultimate fate. But the questions of what the Universe looks like, how it came to be this way and what it’s physically doing have been answered: not by philosophers, poets or theologians, but by the scientific endeavor. And if the new big questions are to be answered — the ones that the answers to the previous big questions raised — it will, again, be science that shows us the way."

What is the Universe? What are those points of light in the night sky? Are there other Suns like our own? Do they have worlds around them? What of the larger structures; what are the spirals and ellipticals out there? How far away are they? And how old is the Universe? And finally, how did it all come to be the way it is today, and how do we know?

These used to be questions for philosophers, poets, and theologians, but for thousands of years, all we got were stories, not answers. Yet in the past 200 years, the enterprise of science has brought us not only the answers to these, but has brought up new questions to ponder, many of which we're on the verge of answering as well. For those of you who aren't in the pacific northwest and can't come to one of my talks, this article is the next best thing to hearing me speak! Come learn how we made sense of the cosmic abyss, and where our deepest scientific endeavors are leading us!
The largest, most daunting mystery in the Universe is the entire Universe itself. Over the past 200 years, here's what we've figured out.
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Cosmology has done an immensely wonderful job of educating our species about the larger scale and where and how we fit into this picture. As Carl Sagan famously said... "The pale blue dot". And yes our understanding of light is cosmological it also gets into the wonderful quirky world of quantum mechanics. And if our present understanding of retrocausality(based off Relativity used to explain Bell's theorem, which inturn, explains the quantum eraser experiment.) that the future does in fact alter the past, then what we do understand on the fundamental building arrangements of energy/matter(information) is lacking. This can be applied specifically to time... or rather what we do and don't know about time. According to Einstein time is distance... acceleration... in space. Hence space-time. A photon doesn't experience "space"... distance. Although an observer observers light taking 8 minutes to arrive on Earth from the photon's perspective it(the photon) never moved. The distance between Earth and the Sun is exactly 0. Now apply this to an electron cloud... the electron is in superposition of all possible positions of this "cloud" or energy level. Which also means that time itself... the distance... is in superposition. Because time is dependent on how fast something is moving... then if the electron is in every position in the cloud then that means different locations and speeds for say the lowest shell for a hydrogen atom. The uncertainty principal comes to mind. So time seems to be the issue... or rather timing to be more specific. Let's figure out how and if time has an actual arrow. 
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Ethan Siegel

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“If you look at rotating galaxies or the motions of galaxies within clusters, there’s a mismatch between the matter we see and the gravitational effects we observe. Even on the largest scales, the way galaxies clump and cluster together cannot be explained without some new physics. Observations show that it can’t be gas, dust, plasma or black holes; there’s truly something unaccounted for. Attempts to modify gravity can solve some of these problems, but the leading explanation is a new type of matter: dark matter.”

Dark matter is a puzzle that’s now more than 80 years old: the presence of all the known, observable, detectable normal matter — the stuff in the standard model — cannot account for the gravitation of the astronomical objects we observe. But despite our inability to create or detect it in a laboratory, we’re certain of its existence in the Universe. The true test of this comes from colliding galaxy clusters, which show a distinct separation between all the known “normal” components, which collide, heat up and emit light, and the gravitational components, which very clearly don’t. At this point, over a dozen distinct colliding clusters show this effect, from some of the smallest known galactic groups to the largest colliding cluster in the Universe: El Gordo.

The full suite of evidence is overwhelming, but this one empirical proof should be all the evidence a reasonable person needs to convince themselves!
The mismatch between the observable mass and the effects of gravity was a problem for much of the 20th century. Here's how we know 'dark matter' must be real.
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Charge is like an arrow(figure of speech)one is a the other is b. As for my idea .it is nothing . because for it to even exist at the science level ? Would be more work then I. Care to bother with. For what? Convince a minority? Why would I do that lol. Digital native progress in the last year alone is proof that. The real mechanism will be discovered by digital native. Not science. To many firewall prevent progress on science front.(math.credential. money flow. Connection etc. Science is too slow. At least science will get to polish it. Grin(like they did for flash bainite)
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Ethan Siegel

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“Cannon herself was responsible for classifying, by hand, more stars in a lifetime than anyone else: around 350,000. She could classify a single star, fully, in approximately 20 seconds, and used a magnifying glass for the majority of the (faint) stars. Her legacy is now nearly 100 years old: on May 9, 1922, the International Astronomical Union formally adopted Annie Jump Cannon’s stellar classification system. With only minor changes having been made in the 94 years since, it is still the primary system in use today.”

A look up at the stars in the night sky shows a clear distinction: some are fainter while others are brighter, some are redder while others are bluer, some are closer while others are much farther away. But what accounts for the differences – some real and some only apparent – between these stars? For most of human history, not only didn’t we know, but any distinction or classification scheme seemed arbitrary. In the 1800s, a new tool, stellar spectroscopy, enabled us to break up the light from stars into its individual wavelengths. By observing a number of “dark” features in these spectra, corresponding to atoms, ions and their absorption lines, we could finally start to make sense of it, and a more objective system.

The person who pieced it all together was Annie Jump Cannon, and her 1901 system is still in use today!
Every star is unique, with its own temperature, size, mass, and composition. But it was one forgotten woman, Annie Jump Cannon, who tied it all together.
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Romen karmakar
Ram reigns

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"Science is how we became great in the first place. It’s only by doing more and better science, and by listening to the robust scientific conclusions, whatever they may say, that we’ll have the greatest version of America possible. But we have to be willing to invest, and we have to be willing to accept and listen to truths that may range from uncomfortable to disconcerting to outrageous. The choice is ours: invest in science and improve, or don’t. We’ve borne the consequences of stagnation from under-investing for many decades now. If we’re serious about making our country (and our world) as great as we possibly can, it’s time to band together, to invest in our future, and — if we really want to go the whole way — to start thinking like scientists whenever we can."

You can't make America great 'again' without looking at what made us great in the first place. It wasn't industry or manufacturing or our morals or our military might; it was our investment in science, research and development that gave us the capabilities to do the extraordinary. Investing in knowledge and fundamental research enabled all the applications that have arisen since. So if you're serious about making America the greatest nation on Earth, maybe the solution isn't to try and support the conclusions you're predisposed to, but rather to support the scientific process and accept whatever answers the scientific endeavor bring to us. Science is what made America great, and investing in it for real is how to make it greater than it's ever been!
If we want to surpass the rest of the world, investing in fundamental, long-term science is the path to our best future.
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As regards to developement of rocket technology and many or post ww2 remainings, please check about action paperclip. 
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Ethan Siegel

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"You know what irks me the most about this topic? I’ve written about it, publicly, for five years now, and how it’s obviously a combination of incompetence and fraud. The thing is, do you know how many LENR researchers have come forward to me and said, “I have met the scientific criteria you laid out. I have an experiment you can perform and results you can reproduce that demonstrate that LENR is happening. Just do this thing “A” and you will see this result “B” that proves it.”

The answer is zero. And the answer is zero because the number of scientifically valid LENR experiments is zero. When I get something wrong about science on the internet (it happens! I’m not perfect! Whaaaat?!), it’s the actual scientists who come and correct me. And they point me to quality work that I can check for myself, and then I change my tune to the correct tune. But there are only sycophants and hangers-on who chide me about cold fusion. Why is that? Why no scientists? Why no one with an independently reproducible experiment?

Is it because they’re really sitting on the Earth-saving, trillion-dollar secret that’s going to change humanity, but everyone who’s stumbled upon the secret is too greedy to make the secret public? Or is it because they don’t have the thing they say they have, and they know if they let real scientists in on what they’re actually doing, they’ll be exposed for the frauds they are?"

From cold fusion to dark matter to elementary particles, nothingness and more, you won't be disappointed by checking out this edition of our comments of the week. Unless, that is, you're not a fan of science. Are you?
“To study things from a scientific standpoint means to take an inventory of them—to find the process in which they are being produced; to connect them with other things; to see things in their causal process. ” -William Harris As is pretty much always the case, it’s been a big week here at Starts With A…
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You are probably good enough to replicate
1922: Helium production from exploding wire observed: American Chemical Society: Irion and Wendt.
This was replicated at SRI using Pd/D and Ni/H nearly every time it was tried. 
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Ethan Siegel

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“This doesn’t necessarily mean that they’re lying, that LENR is impossible or that there’s fraud going on. But it isn’t the job of science to prove that someone is fooling us; it’s the job of a good scientist to prove to the world that we aren’t fooling ourselves when we make an extraordinary claim. As soon as that bar is cleared – and that starts with the people working on this making an extraordinary effort to demonstrate that bar is cleared – we can promote LENR or cold fusion to the realm of real, robust and incredible science. But until that day, we should all remain skeptical.”

The dream of free, unlimited, clean energy depends only on our ability to find a reaction that’s safe, efficient, with abundant reactants, that produces more energy than is required to activate the reaction. Our Sun is a prime example of this, as all it requires is hydrogen – the most abundant element in the Universe – and it produces, through nuclear fusion, an incredible amount of energy each and every second. But an even bigger dream would be to harness this type of fusion reaction here on Earth. While inertial confinement and magnetic confinement fusion, the two most common “hot fusion” scenarios on Earth, have yet to reach the fabled break-even point, there are claims that cold fusion, or Low-Energy Nuclear Reactions (LENR), has done exactly that. Should those claims be taken seriously?

Perhaps. And if we want to do it right, here’s exactly the kind of scientific robustness we’d require in order to do so!
There have been many promises of virtually free, unlimited energy over the years, none of which have panned out. Could this be the one?
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I'm no expert, but to be able to get a LENR at all is a good first step even if it takes more energy than you get out. Plasma & Laser fusion started out the same way.
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“In other words, there’s a limit to what any telescope, in principle, can see. But the spaces between those galaxies – at least to ultraviolet, visible and infrared eyes (the type of light produced by stars) – is truly black. But only, that is, if you view it from space. The spectacular image gracing the top of this article was taken by Yuri Beletsky at the European Southern Observatory, and showcases just how colorful the skies of Earth truly are. Some of what you see is intuitive, while other portions may be quite surprising, and they rely on some intricate physics. Yet that single image encapsulates a whole slew of reasons why the Earth’s night sky is never completely dark.”

Even on the darkest night skies from the most pristine locations on Earth, the night sky is never truly dark. Not even if you look away from the plane of the galaxy, on a moonless night, between the stars and away from any human-made or nature-made sources of illumination. Unlike the views that a telescope like Hubble can get from space, nothing on Earth is ever devoid of photons that have their origin in starlight. That’s because, unlike from space, even the highest-altitude, lowest-turbulence and most pristine locations on Earth still have to contend with our atmosphere. This atmosphere still reflects and refracts light – even if it’s starlight, not sunlight – and exhibits the effect of airglow due to air circulation and interactions with the Sun during the day. No matter where you are on Earth, there’s no escape from 100% of the light.
When all the other lights go out, Earth's night sky shines in its own unique way.
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+Marcin W. Which is why I amended Ethan's text to add "on the surface"... Apparently I forgot to add "(fixed that)" or other similar indicator...
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What are you doing tonight at 6:30 PM?

If you can make it to Winlock, WA, I'll be giving an all-new talk on "Understanding the Cosmic Abyss" at the Winlock Timberland Library tonight, September 20th, at 6:30 pm!

Q&A and book signings afterwards; talk is free and open to the public!
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+Mark Ruhland I am sure I will be there again soon enough!
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Collections Ethan is following
Theoretical Astrophysicist / Writer / Educator
  • NASA's The Space Place
    Columnist, 2013 - present
  • Trap!t
    Head Editor: Science/Health, 2011 - present
  • Starts With A Bang!
    Science Writer, 2008 - present
  • Lewis & Clark College
    Visiting Assistant Professor of Physics, 2009 - 2011
  • University of Portland
    Professor/Lab Coordinator, 2008 - 2009
  • Steward Observatory/University of Arizona
    Postdoctoral Research Associate, 2007 - 2008
  • University of Wisconsin
    Faculty Assistant, 2006 - 2007
  • University of Florida
    Teaching/Research Assistant, Fellow, 2001 - 2006
  • King/Drew Medical Magnet High School
    Teacher, 2000 - 2001
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Bronx, New York - Yonkers, New York - Evanston, Illinois - Torrance, California - Gainesville, Florida - Madison, Wisconsin - Tucson, Arizona - Portland, Oregon - Houston, Texas - Rome, Italy
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Science writer, professor and theoretical astrophysicist
Theoretical Astrophysicist, Science Writer and Communicator, expert in (some aspects of) dark matter and dark energy, physical cosmology, and sometimes professor, teacher and educator.

Creator and writer of Starts With A Bang!, the 2010 Physics Blog of the Year! Author of over 1,000 articles, featured in Esquire, the St. Petersburg Times,'s Page 2, and many others.

Competitive beardsman and amateur acrobat / halloween-costumer extraordinaire.
  • University of Florida College of Liberal Arts and Sciences
    Physics, 2001 - 2006
  • Northwestern University
    Physics, Classics, Integrated Science Program, 1996 - 2000
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