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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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“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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“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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+The Immortal Great Heathen Army "I'm not aware of any immaterial "thing" existing".
-Throw out all numbers !
"Based on what modern ..."
-This is your problem.
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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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"The ability to warp space to “short-cut” your way through the Universe doesn’t change the laws of physics, nor does it change the rate at which time passes for you. In fact, from within your “warp bubble,” all the laws of physics and all of your experience would be the same as for anyone well outside your bubble, or — due to a fun twist of geometry — anyone exactly perpendicular to your direction-of-motion. The ability to outrace a light signal doesn’t mean there’s a preferred reference frame, but it does mean that you need to be willing to pay the price (in terms of energy) to both warp and un-warp that space. It’s not clear that this is feasible.

It’s also worth pointing out that warp drive could lead to the ultimate advantage in forensic investigations. Let’s say a murder occurred an hour ago when you find out about it. All you need to do is “warp” to, say, 65 light-minutes away, open up your super-powerful telescope and view the murder, and viola, the murderer is busted! “Getting away” with a crime would be virtually impossible."

Neutrinos don't stay the same from when they're created, caveats and bonuses of warp drive, the magnetic fields of other worlds, a new type of planet-hunting, reasons for Pluto's non-planethood and the story of life on Earth's possible non-earthly origin! The bonus science is strong this week on our Comments of the Week, so check it out!
“We must free ourselves of the hope that the sea will ever rest. We must learn to sail in high winds.” -Aristotle Onassis Welcome back to the end of another big week at Starts With A Bang! There’s been a lot of fantastic stories that have gone down, including: Can stars escape from the galaxy, with planets…
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“By finding graphite deposits in zircons that are 4.1 billion years old, graphite deposits that show this carbon-12 enhancement, we now have evidence that life on Earth goes back at least 90% of Earth’s history, and possibly even longer! After all, finding the remnants of organic matter in a certain location means the organic matter is at least as old as the location it’s buried in, but it could still be even older. This is so early that it might make you think that perhaps this life didn’t originate here on Earth, but that Earth was born with life. And this could really, truly be the case.”

How old is life on Earth? If all you had to go on was the fossil record, you’d run into severe trouble once you went back more than one or two billion years, as all your rock would have metamorphosed, making examination and identification of fossils impossible. But recently, we’ve discovered another method: to measure the isotopic content of carbon deposits in ancient rock formations. The carbon-12 to carbon-13 ratio is a surefire signature of life, and tells us that life on Earth goes back at least 4.1 billion years: 90% of the age of our planet. Could this be the hint we’ve needed to conclude that life on Earth actually predates the Earth itself? It’s not quite certain, but the beauty of science is we can always test it and find out! Here’s how.
The origin of life is one of the biggest open questions. Could it all have started before our planet was even born?
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Rick is man, therefore Rick is earth and Rick is 6000 years old, I rest my case
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"This is exactly what you’d expect if Pluto were acting like a comet! Objects far beyond Neptune are so cold that they’re covered in ices; New Horizons discovered a world rich in nitrogen, methane and water ice. But Pluto has a highly elliptical orbit, and its perihelion, or closest approach to the Sun, takes it even inside the orbit of Neptune, which it achieved only a few decades ago: in 1989. The closer Pluto is to the Sun, the more the ices on its surface vaporize, forming a hazy atmosphere. That atmosphere can then be gradually stripped away by the high-energy particles of the solar wind, similar to the process that strips Mars’ atmosphere away, only on a much slower, more distant scale."

What, in our Solar System, has a long tail from boiled-off frozen ices? What simultaneously leaves an X-ray signature when the solar wind collides with those boiled-off atoms, kicking electrons out and causing X-ray emissions? If you guessed a comet, you'd be "traditionally" correct, beginning with Comet Hyukutake in 1996. But way out beyond any comets, Pluto does the exact same thing. Thanks to a combination of the New Horizons flyby and observations with the Chandra X-ray observatory, we've been able to measure, verify and learn some incredibly interesting physics about the largest object discovered to date out beyond Neptune. Perhaps most interestingly, it's also the first time we've detected X-rays from beyond SATURN in our Solar System, and ushers in a new era in astronomy: Kuiper belt X-ray observing!

Come get the whole story over on Starts With A Bang today!
It's the first X-ray detection from the Kuiper belt and the first discovery of a comet-like tail around Pluto, even from so far away.
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+Paul Petroff​ thank you for proving my point that only retards believe the world is flat.
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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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Ethan Siegel

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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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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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“So when we talk about the size of an elementary particle, we talk about the search for something truly fundamental. Are the standard model particle truly indivisible? If so, we should be able to keep on going to high and higher energies, and should discover nothing that differs from point-like behavior all the way up to the Planck energy, or down to distance scales of 10-35 meters. Below that distance scale, physics doesn’t give sensible predictions, but we keep approaching it. Perhaps along the way, we’ll find that some (or all) of these particles can be further broken down, or perhaps that they’re made up of strings or membranes, or, alternatively, that they’re simply points all the way down. But all we know to date, as far as the actual sizes of particles, are the sizes of the non-fundamental ones. Everything else is just an upper limit, and the search to get to smaller and smaller scales continues.”

If you take anything in the Universe and want to know what its size is, you simply take something whose length is known and compare. On microscopic scales, it isn’t much different: take something of a known wavelength – like light or another matter particle – and compare. If your wavelength is too big, you’ll pass right through; if your wavelength is the right size or smaller, you’ll interact. This concept of deep inelastic scattering has been successful at measuring the sizes of molecules atoms, atomic nuclei, and individual protons and neutrons. It’s discovered what we consider to be truly fundamental particles: the particles of the Standard Model. But are they truly fundamental? Are they truly point-like? Or is there an actual size to them, after all?
When we split something into its fundamental components, are they really "point-like," or is there a true minimum size in nature?
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“In the end, all we can go off of is what we’ve measured, and admit that the possibilities of what’s uncertain could go in any number of directions. Dark energy appears consistent with a cosmological constant, and there’s no reason to doubt this simplest of models in describing it. But if dark energy gets stronger over time, or if that exponent turns out to be a positive number (even if it’s a small positive number), our Universe might end in a Big Rip instead, where the fabric of space gets torn apart. It’s possible that dark energy may change over time and reverse sign, leading to a Big Crunch instead. Or it’s possible that dark energy may increase in strength and undergo a phase transition, giving rise to a Big Bang once again, and restarting our “cyclical” Universe.”

The discovery of the accelerated expansion of the Universe – and of dark energy behind it – in 1998 was one of the biggest physics revolutions of our lifetime. By measuring these distant galaxies and how their distances and redshifts scale in the Universe, we were able to determine that despite everything we knew about matter and radiation, there was an additional force at play, and it caused distant galaxies to accelerate away from us. The data is now good enough to determine that dark energy is extremely close, if not identical, to the predictions of a cosmological constant. But there are still other theoretical possibilities that are admissible, even if they aren’t favored. Perhaps in the coming decades, we’ll find out that the ‘Big Freeze’ isn’t necessarily where we’re headed in the distant future?
Dark energy has come to dominate the Universe, and leads to a cold, dead, empty fate. But how certain are we that's what we're in for?
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I have no idea. Although I do enjoy thinking about it. I just know that when it comes to even our perceived view of the universe..I don't know shit. Be happy with your intellectual humility 
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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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