“If man is to survive, he will have learned to take a delight in the essential differences between men and between cultures. He will learn that differences in ideas and attitudes are a delight, part of life’s exciting variety, not something to fear.” ―Gene Roddenberry
Well, it happened, everyone! I flew out to the official Star Trek convention in Las Vegas, and the people I met there and the events and panels I attended (and participated in) were largely fabulous! Best of all, I got to line up a number of future podcasts about science, Star Trek, and everything in between, so stay tuned in the coming weeks and months for more. In fact, there’s a new one up already: the Trolling With Logic podcast!
- Does Light Always Move At The Same Speed? (for Ask Ethan),
- Universe’s Largest Black Hole May Have An Explanation At Last (for Mostly Mute Monday),
- Maryam Mirzakhani, A Candle Illuminating The Dark (by Paul Halpern, about an amazing life),
- How to catch the Perseids and beat the almost-full Moon,
- Ripples In Spacetime: From Einstein To LIGO And Beyond, and
- America’s Previous Coast-To-Coast Eclipse Almost Proved Einstein Right.
There were a lot of old topics that you kept bringing up, but if that’s what you’ve been interested in, who am I to say no to more science of whatever flavor you’re into? Let’s continue the discussion right now — and kudos to those of you who caught my one mistake this week — on this edition of our comments of the week!
Correctly calibrated satellite data, as well as the more recent temperature data up through 2016, shows that climate predictions and observations are perfectly in line with one another. Image credit: HadCRUT4.5, Cowtan & Way, NASA GISTEMP, NOAA GlobalTemp, BEST, via Ed Hawkins at Climate Lab Book.
From Denier on climate science, and specifically models vs. predictions: “If you feel the need to shout me down so that you can use your platform to present the approved “full suite of evidence” and leave out “misleading, not to be included in the full suite because they muddy the facts” science such as Santer(2017), NOAA data that shows falling relative humidity, etc., just let me know.”
No one is shouting you down. Don’t confuse “shouting you down” with “ignoring the non-relevant parts of your argument,” which is, as you know as you make it, most of your argument. I have repeatedly said:
- The climate models are flawed and do have systematic errors, but they are not as fundamentally flawed, quantitatively, as sites like Heartland claim.
- The climate models, even with their flaws, do a much better job than “overestimating the actual warming in 95%+ of the models,” as Heartland claimed.
- The main thrust of the climate science story remains unchanged from the standard narrative, which is:
- The Earth is warming,
- Humans are the primary cause,
- It is bad,
- And we can do something about it if we try,
- Your red herrings of Santer et al. (2017) and the falling humidity from the NOAA data represent small corrections and, in the Santer (2017) case, improvements to climate modeling and measuring, and do not change the story.
Economic studies are not part of the climate science studies. As, again, I have repeatedly said, the full suite of scientific evidence in climate science is what you must consider before considering economic and societal impacts. Then, the full suite of all impacts — although this is now a matter of my opinion — is what should be considered before making policy. What we have instead, as the status quo, is policy makers making policy based on ideology that does not accept the full suite of scientific evidence in climate science. You yourself, like many others here, do not do that, and still refer to outdated and incorrectly calibrated UAH data when you make arguments, and do so unapologetically.
Yes, I do see you deliberately muddying the waters, because I believe your intent is to support the conclusion of “allow unregulated and untaxed emissions to continue” regardless of what the quantitative impacts are. If that is not your intent, you should demonstrate something different than what you’ve demonstrated so far, because I don’t believe you have any interest in the scientific truth in this matter. You have made no convincing arguments toward that end. But you cannot argue your way to a different conclusion than what the evidence presents. That might work in many arenas of life — and it may even work to fool the majority of the public — but it doesn’t change the scientific facts.
The interplay between the atmosphere, clouds, moisture, land processes and the ocean all governs the evolution of Earth’s equilibrium temperature. Image credit: Smithsonian Air and Space Museum.
From John on how to make a difference: “[quoting me]“So maybe I need to take a different line of argument if I want to make a difference.”
In what way(s) do you thing you can make a difference other than by providing the best Science Explanations you can?”
I think that’s the biggest difference-maker I can do, and I anticipate continuing to do so. But perhaps I need to address the falsehoods in a different regard. If I allow it to be presented as a “some scientists say this thing, but others say that thing,” it gives the impression of a false legitimacy to the opinions of a few fringe scientists, and undercuts the overwhelming evidence in favor of the consensus conclusion.
I don’t write about variable speed-of-light cosmology, even though there are legitimate (fringe) scientists working on it. I don’t write about spatially anisotropic variations in the fine-structure constant, even though John Webb’s research is intriguing, if not necessarily compelling. I don’t write about the ekpyrotic Universe alternative to inflation, even though a small number of high-profile cosmologists support it. Why should I grant that legitimacy to those who claim that:
- The Earth isn’t warming, or
- Humans aren’t the cause, or
- Even if it happens, it will be a good thing?
That is how I’m considering making a difference: by putting good science out there without providing any undeserved legitimacy to the fringe alternatives. I am not 100% sure how to execute that, but that’s what I’m thinking about.
An illustration of gravitational lensing showcases how background galaxies — or any light path — is distorted by the presence of an intervening mass, such as a foreground galaxy cluster. Image credit: NASA / ESA.
From CFT on (suddenly?) denying general relativity: “How many masses can you put into the same space time matrix? And have them, you know, interact?”
An arbitrary number. Really. Just because you cannot write down a solution to the Einstein equations, analytically, with an arbitrary number of masses, does not mean you cannot do relativity with them. You can’t solve the Navier-Stokes equations analytically either, except in some very simple cases, but you don’t deny fluid dynamics. We can solve arbitrarily difficult problems to arbitrary precision, numerically, and that is in fact how we do it. This is how we solve all classes of problems in all sorts of robust fields — perturbatively — like quantum field theory. Do not conflate “I don’t have an exact, analytical solution” which, practically, we do not (usually) do, with “this theory is useless,” which it most assuredly is not.
How do you think we calculate black hole inspirals, mergers, binary pulsar decay rates, ultramassive black hole precession, and more? Numerical relativity. And when we do the observations, the agreement is remarkable.
The event horizon of a black hole is a spherical or spheroidal region from which nothing, not even light, can escape. But outside the event horizon, anything that isn’t yet inside has, with the right energy inputs, a chance to get out. Image credit: NASA; Jörn Wilms (Tübingen) et al.; ESA.
From Adam on answering his question about falling into a black hole with a tether: “Thank you for your patience Ethan! My own physics education was undergrad only and multiple decades ago at that. Questions above our level were usually rebuffed, so thanks again!”
Adam, as you can see, I don’t get a whole lot of appreciation on this blog. But I do very much know that the majority of people who read what I put out there are interested, curious, and supportive of what I’m doing. I know the appreciation is out there, but I truly appreciate hearing it. That this encouraging comment was left just prior to my birthday was a big deal to me, so as I celebrate the start of my 40th trip around the Sun, I want to thank you for this. In other words, you’re more than welcome.
A fly-by of a large enough mass could change the orbit of a planet. But is there any energy saved?
From Frank on changing the orbit of another world by adding a second world into the mix: “I admit I didn’t realize total mass in the asteroid belt was so small. But still there maybe a solution by stealing some moons of Jupiter etc (assuming we could have the energy/tech in distant future).”
I mean, you could, but what is the advantage? What you’re talking about is changing the orbit of a large mass, imparting energy to it, causing it to fly-by another large mass, and thereby to change that mass’s orbit. Sure, you can do that. But the energy cost to unbind, say, Callisto from Jupiter, send it towards Mars, and have it change Mars’ orbit to migrate wherever you want to have it migrate to, is no less than the energy cost to simply change Mars’ orbit without the middle-man. It’s a possible solution, but what is the advantage? I don’t see it.
Humans can routinely view the Earth from outer space, orbiting our world once every 90 minutes. The imprint of the human impact on our world, particularly at night, is easily visible. Image credit: NASA / International Space Station.
From Michael Mooney on changing the rotation of Earth: “Do you believe that an observer traveling at high speed can affect the spin and orbit of Planet Earth?”
This was an interesting question for two reasons to me, even though it occurred way down in a thread that largely wasn’t interesting to me. The first reason I found it interesting is because it gives a great opportunity to talk about the difference between an object moving with a constant velocity or angular velocity, and an object with a changing velocity or angular velocity. If you are an observer who was at rest and accelerates to a large velocity/angular velocity, you do change the motion/rotation of the Earth. This is true in relativity… but it’s also true via Newton’s laws. That’s the “equal and opposite reaction” imparted by your change in momentum (or angular momentum).
But the other reason I found it interesting is because you asked “do you believe” to someone. Why would you ever ask that question in physics? Do you believe that 0 + 5 = 05? Do you believe that 7 + 5 = 75? Do you believe that Plymouth rock weighs 10^22 kilograms? I assert that beliefs, when concerning questions that have demonstrable, definitive answers, aren’t “right or wrong” as much as silly and useless. It’s a free world (mostly), so believe what you want. But don’t expect anyone to take seriously the substitute of a belief for actual, existing knowledge. I think that goes for everyone.
Zangief is always lurking…
From MobiusKlein on the topic of Pentcho Valev: “Pentcho Valev, you are not contributing anything to the comments except walls of text.
Please stop.
Ethan, please ask Pentcho Valev to stop too.”
No. I won’t ask him to stop. This week, in my estimation, has been too much. particularly his ongoing cut-and-paste hack jobs. His presence has degraded the quality of the comment section of this blog, and has no positives to offset that. As of this moment, he is now banned.
The first pendulum clock, as designed by Christiaan Huygens, provided the first accurate measurement of time for humans that didn’t rely on astronomical phenomena. Atomic clocks can now achieve precisions better than ~10^-15 seconds per day.
From Naked Bunny with a Whip on absolute time: “Even the most rudimentary study would tell you that Special Relativity overthrew the assumption of time as a constant.”
One of the really fun, relatively early direct tests of relativity — both special and general, together — is told in Govert Schilling’s book, Ripples in Spacetime. Imagine you had an atomic clock on the ground, and an identical, synchronized (initially) atomic clock that you took with you, wherever you went. And you took a journey, up in an airplane, at a specific speed and a specific altitude, moving with the rotation of the Earth. Then, you did the same exact experiment, except this time, you moved in the airplane at the same speed and altitude, except this time you moved against the rotation of the Earth.
How many times would the clock on the ground, the clock in the counterclockwise-moving (with the Earth) airplane, and the clockwise-moving (against the Earth) airplane “tick” away during those respective journeys? If you want to get the answer that agrees with the experiment, you need to include everything: the motion (and direction) of the airplane, the rotation (including direction) of the Earth, and the effects of the gravitational field/potential at every location along each clock’s journey. The idea that time could be a constant between all three observers was directly disproved as soon as we were able to measure to the necessary accuracies. But the notion that relativity provided the right answer is far more powerful, because it tells you how time actually works!
My original caption, “An ultra-distant quasar showing plenty of evidence for a supermassive black hole at its center. How that black hole got so massive so quickly is a topic of contentious scientific debate, but may have an answer that fits within our standard theories.” may be flawed. Image credit: X-ray: NASA/CXC/Univ of Michigan/R.C.Reis et al; Optical: NASA/STScI.
From Michael Richmond on the quasar shown in the above picture: “The first image on this page has the caption “An ultra-distant quasar showing plenty of evidence for a supermassive black hole at its center. ” The picture is an HST image of the quadruple gravitational lens RX J1131-1231, in which the foreground lens is at redshift z=0.295 and the background quasar at z=0.658. Those redshifts indicate that the objects are very distant from the Sun, certainly, but “ultra-distant” seems a strange term to use; astronomers have catalogued thousands of quasars at redshifts larger than z=1, some up to z=6.”
You know, this is an extremely good catch. I came across this image in the wild, where it was described as a quasar at a distance of 12.4 billion light years away, where distances were (incorrectly) equated to lookback times, a lazy convention that many scientists and science writers still (unfortunately) use. Since the lazy convention gave almost the same lookback time as the z=3.3 quasar I discussed, I thought I would use it as a proxy for the one I wished there was an optical picture of: S5 0014+81. (Alas, I can still find none.)
But it is not at a distance of 12.4 billion light years, but much closer than that. You have identified it correctly, and I owe myself admonishment for leading you astray with the use of an image that does not reflect what I was attempting to illustrate. Thank you for keeping me honest.
Two neutron stars colliding, which is the primary source of many of the heaviest periodic table elements in the Universe. About 3-5% of the mass gets expelled in such a collision; the rest becomes a single black hole. Image credit: Dana Berry, SkyWorks Digital, Inc..
From Graham dickin on making truly ultra-massive elements: “When the big bang happened we had hydrogen and helium plus a small amount of others the amazed over time and created an environment to produce the atomic table .What if this is still being produced in the centre of black holes .That in there the atomic number 1000 exists or even 1 million or one billion .”
So, you want to make an ultra-massive element, do you? Unfortunately, black holes aren’t going to be the way to do it. Unless, that is, you mean the by-products of forming a black hole in a very specific fashion. When you collide two neutron stars, you’re basically colliding two giant atomic nuclei, each with about 10^30 (okay, “a few” 10^30) neutrons in that nucleus. So, you start out a nucleus with about 1,000,000,000,000,000,000,000,000,000,000 nucleons inside, but since they’re all neutrons, it’s not really interesting with respect to the periodic table.
When these neutron stars collide, however, about 3% of the total mass flies off outwards, while the other 97% collapses into a black hole. But of those 3%, you get “chunks” that fill out the very high ends of the periodic table, producing the majority of gold, platinum, palladium, uranium, plutonium, and other very-heavy elements in the Universe… but they also produce elements that most likely have not yet been discovered, containing perhaps hundreds or thousands of protons, or even more. If we could smash two neutron stars together and examine the debris up close, we’d be able to find these ultra-heavy elements for ourselves, even for the tiniest of timescales.
A room where the walls, even if completely covered with mirrors, would never have every location illuminated, was a mathematically interesting conjecture that was only solved recently. Image credit: Mathematical Sciences Research Institute (MSRI) / Numberphile / Brady Haran / Howard Masur.
From Denier on Maryam Mirzakhani’s contributions: “The Illuminated Room problem was solved by Roger Penrose over 20 years before Mirzakhani was born using curved mirrors. It was solved by George Tokarsky in 1995 using the 26-sided room in the image you’ve got in the center of your article. His solution had NOTHING to do with Mirzakhani. A more elegant solution was authored by David Castro in 1997 with a 24-sided room that again had nothing to do with anything Mirzakhani was working on as an undergrad in Iran at the time.”
The work of Penrose, Tokarsky, and Castro is all as you say. But how does this detract from the contributions that Mirzakhani subsequently made to the Illuminated Room problem? Mathematicians don’t say, “oh, that’s a tough problem, but I found a solution, and now we’re done.” Nope. Mathematicians will math a problem until it can be mathed no more, until it has given up all of its secrets in every exhaustible fashion. Evolution didn’t end with Darwin, and the Illuminated Room problem didn’t end with Penrose, or Tokarsky, or Castro, or Mirzakhani. But that does not diminish the accomplishments of any of them, as dean rightly points out.
Image credit: NASA / George Varros.
From Ragtag Media on the speed of darkness: “With each meteor falling, does the darkness collapse around the trail of each photon of light at the same speed of light or slower?”
Darkness, as we have gone over many times before (although not recently), does not have a speed, because it is not a physical “thing.” Each photon moves at the speed of light; darkness is the absence of photons. Observers on Earth that are viewing the same meteor from different locations and orientations will see darkness propagate at different speeds, but it isn’t a sensible thing to measure. You’re welcome to nail down a better definition of what you’re trying to measure than “darkness collapsing around the trail of each photon,” but I’m afraid I don’t understand what you mean.
For the first time in almost 40 years, the path of the moon’s shadow passes through the continental United States. This visualization shows the Earth, moon, and sun at 17:05:40 UTC during the eclipse. Image credit: NASA’s Scientific Visualization Studio.
And for the last comment this week, I’ll give it to MobiusKlein, whose comment in response to Pentcho Valev’s Friday article was as follows: “And nobody since 1919 has bothered to do this test during an eclipse, with better equipment? Or has Big Einstein silenced them all? Watch out, YOU may be the victim of BE’s reign of ERROR!”
I am glad that MobiusKlein’s very sarcastic response was here. Science, just to be extremely clear, does not rely on one experiment to settle the matter, and then never perform the experiment again. No; we are constantly checking our results, gathering more data to improved precision, and looking for flaws in our predictions at the 10% level, then 1%, then 0.1%, then 0.01%, etc.
The story of scientific investigation is a story of ever-increasing precision and ever decreasing uncertainty, and one that I value and will keep telling, no matter what some (or many, or even most, sometimes) of the commenters here or elsewhere say. The scientific truth is too important, even if (and when) public opinion is against it. It’s why I’m here, and it’s what I’ve been doing — somewhat successfully, mind you — for over nine years now. In fact, when January rolls around, that will mark 10 years since the inception of Starts With A Bang. That we’re all here, thinking about the Universe and how it all works, is something worth celebrating, even when it’s difficult.
Thank you all for joining me, and looking forward to all the wonderful moments to come in the journey ahead!
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“If man is to survive, he will have learned to take a delight in the essential differences between men and between cultures. He will learn that differences in ideas and attitudes are a delight, part of life’s exciting variety, not something to fear.” ―Gene Roddenberry
Well, it happened, everyone! I flew out to the official Star Trek convention in Las Vegas, and the people I met there and the events and panels I attended (and participated in) were largely fabulous! Best of all, I got to line up a number of future podcasts about science, Star Trek, and everything in between, so stay tuned in the coming weeks and months for more. In fact, there’s a new one up already: the Trolling With Logic podcast!
- Does Light Always Move At The Same Speed? (for Ask Ethan),
- Universe’s Largest Black Hole May Have An Explanation At Last (for Mostly Mute Monday),
- Maryam Mirzakhani, A Candle Illuminating The Dark (by Paul Halpern, about an amazing life),
- How to catch the Perseids and beat the almost-full Moon,
- Ripples In Spacetime: From Einstein To LIGO And Beyond, and
- America’s Previous Coast-To-Coast Eclipse Almost Proved Einstein Right.
There were a lot of old topics that you kept bringing up, but if that’s what you’ve been interested in, who am I to say no to more science of whatever flavor you’re into? Let’s continue the discussion right now — and kudos to those of you who caught my one mistake this week — on this edition of our comments of the week!
Correctly calibrated satellite data, as well as the more recent temperature data up through 2016, shows that climate predictions and observations are perfectly in line with one another. Image credit: HadCRUT4.5, Cowtan & Way, NASA GISTEMP, NOAA GlobalTemp, BEST, via Ed Hawkins at Climate Lab Book.
From Denier on climate science, and specifically models vs. predictions: “If you feel the need to shout me down so that you can use your platform to present the approved “full suite of evidence” and leave out “misleading, not to be included in the full suite because they muddy the facts” science such as Santer(2017), NOAA data that shows falling relative humidity, etc., just let me know.”
No one is shouting you down. Don’t confuse “shouting you down” with “ignoring the non-relevant parts of your argument,” which is, as you know as you make it, most of your argument. I have repeatedly said:
- The climate models are flawed and do have systematic errors, but they are not as fundamentally flawed, quantitatively, as sites like Heartland claim.
- The climate models, even with their flaws, do a much better job than “overestimating the actual warming in 95%+ of the models,” as Heartland claimed.
- The main thrust of the climate science story remains unchanged from the standard narrative, which is:
- The Earth is warming,
- Humans are the primary cause,
- It is bad,
- And we can do something about it if we try,
- Your red herrings of Santer et al. (2017) and the falling humidity from the NOAA data represent small corrections and, in the Santer (2017) case, improvements to climate modeling and measuring, and do not change the story.
Economic studies are not part of the climate science studies. As, again, I have repeatedly said, the full suite of scientific evidence in climate science is what you must consider before considering economic and societal impacts. Then, the full suite of all impacts — although this is now a matter of my opinion — is what should be considered before making policy. What we have instead, as the status quo, is policy makers making policy based on ideology that does not accept the full suite of scientific evidence in climate science. You yourself, like many others here, do not do that, and still refer to outdated and incorrectly calibrated UAH data when you make arguments, and do so unapologetically.
Yes, I do see you deliberately muddying the waters, because I believe your intent is to support the conclusion of “allow unregulated and untaxed emissions to continue” regardless of what the quantitative impacts are. If that is not your intent, you should demonstrate something different than what you’ve demonstrated so far, because I don’t believe you have any interest in the scientific truth in this matter. You have made no convincing arguments toward that end. But you cannot argue your way to a different conclusion than what the evidence presents. That might work in many arenas of life — and it may even work to fool the majority of the public — but it doesn’t change the scientific facts.
The interplay between the atmosphere, clouds, moisture, land processes and the ocean all governs the evolution of Earth’s equilibrium temperature. Image credit: Smithsonian Air and Space Museum.
From John on how to make a difference: “[quoting me]“So maybe I need to take a different line of argument if I want to make a difference.”
In what way(s) do you thing you can make a difference other than by providing the best Science Explanations you can?”
I think that’s the biggest difference-maker I can do, and I anticipate continuing to do so. But perhaps I need to address the falsehoods in a different regard. If I allow it to be presented as a “some scientists say this thing, but others say that thing,” it gives the impression of a false legitimacy to the opinions of a few fringe scientists, and undercuts the overwhelming evidence in favor of the consensus conclusion.
I don’t write about variable speed-of-light cosmology, even though there are legitimate (fringe) scientists working on it. I don’t write about spatially anisotropic variations in the fine-structure constant, even though John Webb’s research is intriguing, if not necessarily compelling. I don’t write about the ekpyrotic Universe alternative to inflation, even though a small number of high-profile cosmologists support it. Why should I grant that legitimacy to those who claim that:
- The Earth isn’t warming, or
- Humans aren’t the cause, or
- Even if it happens, it will be a good thing?
That is how I’m considering making a difference: by putting good science out there without providing any undeserved legitimacy to the fringe alternatives. I am not 100% sure how to execute that, but that’s what I’m thinking about.
An illustration of gravitational lensing showcases how background galaxies — or any light path — is distorted by the presence of an intervening mass, such as a foreground galaxy cluster. Image credit: NASA / ESA.
From CFT on (suddenly?) denying general relativity: “How many masses can you put into the same space time matrix? And have them, you know, interact?”
An arbitrary number. Really. Just because you cannot write down a solution to the Einstein equations, analytically, with an arbitrary number of masses, does not mean you cannot do relativity with them. You can’t solve the Navier-Stokes equations analytically either, except in some very simple cases, but you don’t deny fluid dynamics. We can solve arbitrarily difficult problems to arbitrary precision, numerically, and that is in fact how we do it. This is how we solve all classes of problems in all sorts of robust fields — perturbatively — like quantum field theory. Do not conflate “I don’t have an exact, analytical solution” which, practically, we do not (usually) do, with “this theory is useless,” which it most assuredly is not.
How do you think we calculate black hole inspirals, mergers, binary pulsar decay rates, ultramassive black hole precession, and more? Numerical relativity. And when we do the observations, the agreement is remarkable.
The event horizon of a black hole is a spherical or spheroidal region from which nothing, not even light, can escape. But outside the event horizon, anything that isn’t yet inside has, with the right energy inputs, a chance to get out. Image credit: NASA; Jörn Wilms (Tübingen) et al.; ESA.
From Adam on answering his question about falling into a black hole with a tether: “Thank you for your patience Ethan! My own physics education was undergrad only and multiple decades ago at that. Questions above our level were usually rebuffed, so thanks again!”
Adam, as you can see, I don’t get a whole lot of appreciation on this blog. But I do very much know that the majority of people who read what I put out there are interested, curious, and supportive of what I’m doing. I know the appreciation is out there, but I truly appreciate hearing it. That this encouraging comment was left just prior to my birthday was a big deal to me, so as I celebrate the start of my 40th trip around the Sun, I want to thank you for this. In other words, you’re more than welcome.
A fly-by of a large enough mass could change the orbit of a planet. But is there any energy saved?
From Frank on changing the orbit of another world by adding a second world into the mix: “I admit I didn’t realize total mass in the asteroid belt was so small. But still there maybe a solution by stealing some moons of Jupiter etc (assuming we could have the energy/tech in distant future).”
I mean, you could, but what is the advantage? What you’re talking about is changing the orbit of a large mass, imparting energy to it, causing it to fly-by another large mass, and thereby to change that mass’s orbit. Sure, you can do that. But the energy cost to unbind, say, Callisto from Jupiter, send it towards Mars, and have it change Mars’ orbit to migrate wherever you want to have it migrate to, is no less than the energy cost to simply change Mars’ orbit without the middle-man. It’s a possible solution, but what is the advantage? I don’t see it.
Humans can routinely view the Earth from outer space, orbiting our world once every 90 minutes. The imprint of the human impact on our world, particularly at night, is easily visible. Image credit: NASA / International Space Station.
From Michael Mooney on changing the rotation of Earth: “Do you believe that an observer traveling at high speed can affect the spin and orbit of Planet Earth?”
This was an interesting question for two reasons to me, even though it occurred way down in a thread that largely wasn’t interesting to me. The first reason I found it interesting is because it gives a great opportunity to talk about the difference between an object moving with a constant velocity or angular velocity, and an object with a changing velocity or angular velocity. If you are an observer who was at rest and accelerates to a large velocity/angular velocity, you do change the motion/rotation of the Earth. This is true in relativity… but it’s also true via Newton’s laws. That’s the “equal and opposite reaction” imparted by your change in momentum (or angular momentum).
But the other reason I found it interesting is because you asked “do you believe” to someone. Why would you ever ask that question in physics? Do you believe that 0 + 5 = 05? Do you believe that 7 + 5 = 75? Do you believe that Plymouth rock weighs 10^22 kilograms? I assert that beliefs, when concerning questions that have demonstrable, definitive answers, aren’t “right or wrong” as much as silly and useless. It’s a free world (mostly), so believe what you want. But don’t expect anyone to take seriously the substitute of a belief for actual, existing knowledge. I think that goes for everyone.
Zangief is always lurking…
From MobiusKlein on the topic of Pentcho Valev: “Pentcho Valev, you are not contributing anything to the comments except walls of text.
Please stop.
Ethan, please ask Pentcho Valev to stop too.”
No. I won’t ask him to stop. This week, in my estimation, has been too much. particularly his ongoing cut-and-paste hack jobs. His presence has degraded the quality of the comment section of this blog, and has no positives to offset that. As of this moment, he is now banned.
The first pendulum clock, as designed by Christiaan Huygens, provided the first accurate measurement of time for humans that didn’t rely on astronomical phenomena. Atomic clocks can now achieve precisions better than ~10^-15 seconds per day.
From Naked Bunny with a Whip on absolute time: “Even the most rudimentary study would tell you that Special Relativity overthrew the assumption of time as a constant.”
One of the really fun, relatively early direct tests of relativity — both special and general, together — is told in Govert Schilling’s book, Ripples in Spacetime. Imagine you had an atomic clock on the ground, and an identical, synchronized (initially) atomic clock that you took with you, wherever you went. And you took a journey, up in an airplane, at a specific speed and a specific altitude, moving with the rotation of the Earth. Then, you did the same exact experiment, except this time, you moved in the airplane at the same speed and altitude, except this time you moved against the rotation of the Earth.
How many times would the clock on the ground, the clock in the counterclockwise-moving (with the Earth) airplane, and the clockwise-moving (against the Earth) airplane “tick” away during those respective journeys? If you want to get the answer that agrees with the experiment, you need to include everything: the motion (and direction) of the airplane, the rotation (including direction) of the Earth, and the effects of the gravitational field/potential at every location along each clock’s journey. The idea that time could be a constant between all three observers was directly disproved as soon as we were able to measure to the necessary accuracies. But the notion that relativity provided the right answer is far more powerful, because it tells you how time actually works!
My original caption, “An ultra-distant quasar showing plenty of evidence for a supermassive black hole at its center. How that black hole got so massive so quickly is a topic of contentious scientific debate, but may have an answer that fits within our standard theories.” may be flawed. Image credit: X-ray: NASA/CXC/Univ of Michigan/R.C.Reis et al; Optical: NASA/STScI.
From Michael Richmond on the quasar shown in the above picture: “The first image on this page has the caption “An ultra-distant quasar showing plenty of evidence for a supermassive black hole at its center. ” The picture is an HST image of the quadruple gravitational lens RX J1131-1231, in which the foreground lens is at redshift z=0.295 and the background quasar at z=0.658. Those redshifts indicate that the objects are very distant from the Sun, certainly, but “ultra-distant” seems a strange term to use; astronomers have catalogued thousands of quasars at redshifts larger than z=1, some up to z=6.”
You know, this is an extremely good catch. I came across this image in the wild, where it was described as a quasar at a distance of 12.4 billion light years away, where distances were (incorrectly) equated to lookback times, a lazy convention that many scientists and science writers still (unfortunately) use. Since the lazy convention gave almost the same lookback time as the z=3.3 quasar I discussed, I thought I would use it as a proxy for the one I wished there was an optical picture of: S5 0014+81. (Alas, I can still find none.)
But it is not at a distance of 12.4 billion light years, but much closer than that. You have identified it correctly, and I owe myself admonishment for leading you astray with the use of an image that does not reflect what I was attempting to illustrate. Thank you for keeping me honest.
Two neutron stars colliding, which is the primary source of many of the heaviest periodic table elements in the Universe. About 3-5% of the mass gets expelled in such a collision; the rest becomes a single black hole. Image credit: Dana Berry, SkyWorks Digital, Inc..
From Graham dickin on making truly ultra-massive elements: “When the big bang happened we had hydrogen and helium plus a small amount of others the amazed over time and created an environment to produce the atomic table .What if this is still being produced in the centre of black holes .That in there the atomic number 1000 exists or even 1 million or one billion .”
So, you want to make an ultra-massive element, do you? Unfortunately, black holes aren’t going to be the way to do it. Unless, that is, you mean the by-products of forming a black hole in a very specific fashion. When you collide two neutron stars, you’re basically colliding two giant atomic nuclei, each with about 10^30 (okay, “a few” 10^30) neutrons in that nucleus. So, you start out a nucleus with about 1,000,000,000,000,000,000,000,000,000,000 nucleons inside, but since they’re all neutrons, it’s not really interesting with respect to the periodic table.
When these neutron stars collide, however, about 3% of the total mass flies off outwards, while the other 97% collapses into a black hole. But of those 3%, you get “chunks” that fill out the very high ends of the periodic table, producing the majority of gold, platinum, palladium, uranium, plutonium, and other very-heavy elements in the Universe… but they also produce elements that most likely have not yet been discovered, containing perhaps hundreds or thousands of protons, or even more. If we could smash two neutron stars together and examine the debris up close, we’d be able to find these ultra-heavy elements for ourselves, even for the tiniest of timescales.
A room where the walls, even if completely covered with mirrors, would never have every location illuminated, was a mathematically interesting conjecture that was only solved recently. Image credit: Mathematical Sciences Research Institute (MSRI) / Numberphile / Brady Haran / Howard Masur.
From Denier on Maryam Mirzakhani’s contributions: “The Illuminated Room problem was solved by Roger Penrose over 20 years before Mirzakhani was born using curved mirrors. It was solved by George Tokarsky in 1995 using the 26-sided room in the image you’ve got in the center of your article. His solution had NOTHING to do with Mirzakhani. A more elegant solution was authored by David Castro in 1997 with a 24-sided room that again had nothing to do with anything Mirzakhani was working on as an undergrad in Iran at the time.”
The work of Penrose, Tokarsky, and Castro is all as you say. But how does this detract from the contributions that Mirzakhani subsequently made to the Illuminated Room problem? Mathematicians don’t say, “oh, that’s a tough problem, but I found a solution, and now we’re done.” Nope. Mathematicians will math a problem until it can be mathed no more, until it has given up all of its secrets in every exhaustible fashion. Evolution didn’t end with Darwin, and the Illuminated Room problem didn’t end with Penrose, or Tokarsky, or Castro, or Mirzakhani. But that does not diminish the accomplishments of any of them, as dean rightly points out.
Image credit: NASA / George Varros.
From Ragtag Media on the speed of darkness: “With each meteor falling, does the darkness collapse around the trail of each photon of light at the same speed of light or slower?”
Darkness, as we have gone over many times before (although not recently), does not have a speed, because it is not a physical “thing.” Each photon moves at the speed of light; darkness is the absence of photons. Observers on Earth that are viewing the same meteor from different locations and orientations will see darkness propagate at different speeds, but it isn’t a sensible thing to measure. You’re welcome to nail down a better definition of what you’re trying to measure than “darkness collapsing around the trail of each photon,” but I’m afraid I don’t understand what you mean.
For the first time in almost 40 years, the path of the moon’s shadow passes through the continental United States. This visualization shows the Earth, moon, and sun at 17:05:40 UTC during the eclipse. Image credit: NASA’s Scientific Visualization Studio.
And for the last comment this week, I’ll give it to MobiusKlein, whose comment in response to Pentcho Valev’s Friday article was as follows: “And nobody since 1919 has bothered to do this test during an eclipse, with better equipment? Or has Big Einstein silenced them all? Watch out, YOU may be the victim of BE’s reign of ERROR!”
I am glad that MobiusKlein’s very sarcastic response was here. Science, just to be extremely clear, does not rely on one experiment to settle the matter, and then never perform the experiment again. No; we are constantly checking our results, gathering more data to improved precision, and looking for flaws in our predictions at the 10% level, then 1%, then 0.1%, then 0.01%, etc.
The story of scientific investigation is a story of ever-increasing precision and ever decreasing uncertainty, and one that I value and will keep telling, no matter what some (or many, or even most, sometimes) of the commenters here or elsewhere say. The scientific truth is too important, even if (and when) public opinion is against it. It’s why I’m here, and it’s what I’ve been doing — somewhat successfully, mind you — for over nine years now. In fact, when January rolls around, that will mark 10 years since the inception of Starts With A Bang. That we’re all here, thinking about the Universe and how it all works, is something worth celebrating, even when it’s difficult.
Thank you all for joining me, and looking forward to all the wonderful moments to come in the journey ahead!
from ScienceBlogs http://ift.tt/2wxowNP
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