Fastest star ever seen is moving at 8% the speed of light
phys.org
phys.org
They're multi-layer stacks of CCD observations filtered by frequency range, with false colors then assigned, not three RGB layers. IIRC, typically there's 7 - 11 ranges, depending on the instrument.
So one of the layers included in the depiction might be infrared, then false-colored into something the eye can handle.
Source: I worked in remote sensing.
One of my frustrations with ML is that almost no one seems to be training on HDR data. It's all 8-bit RGB. There is a big opportunity here to train GANs on raw sensor data.
But that raises the question of which file formats to focus on. Since you have lots of image processing experience, I'm very interested in what the data formats were like at your job. Was it proprietary formats? If so, were there any advantages over e.g. the RAW file format? Is RAW sufficient for standardizing "everything necessary to turn photon readings into a photograph that appeals to the human eye"? E.g. if I gather thousands of RAW photos, do I need any other information not present in the RAW file?
Mainly I am interested in any insights you gained on the job: you might know of some unique advantage that certain data formats have over others. I'm extremely interested in training ML models to synthesize what comes into a camera (photon readings), as opposed to what the world looks like to the human eye (RGB values).
(I apologize for not phrasing my questions more carefully. It's late. The essence is that right now, most ML training operate in terms of RGB, yet there seems to be many advantages to operating in "photon space". The trouble is, it's effortless to gather millions of RGB photos -- but it seems very difficult to gather a million RAW photos. I'm hoping someone knows of a massive trove of "some kind of raw data that can be turned into RGB values" – maybe that's RAW, maybe it's something else. Whatever it is, once I have it, I can feed it through an ML model.)
Even if you get millions of RAW photos they will come from different sensors with different properties (noise, sensitivity, mosaic, orientation...) and you need to to normalize them all. sRGB is most common normalization target for which all prosumer cameras are optimized for.
The format is not really important here as it is usually array of pixels. You need more bits and resolution? Fine, but you also get more useless noise.
A library like libraw reads most RAW files and can give you an appropiately (for the sensor used) debayered RGB image. These images aren't in a defined color space; they're specific to every camera/sensor.
In the moving pictures space OpenEXR is a common format for "arbitrary" images, since it allows any number of channels each with different formats (e.g. you can have a file with 27 channels per pixel, some of which are float and some of which are integer).
[1] E.g. 12 bit log encoding gives even resolution across more of the dynamic range; a linear encoding gives half of each range to the brighter stop.
[2] Sensors that don't have PGAs simply have a fixed sensitivity. If the camera offers an ISO setting, it is emulated in the digital domain by pulling the image.
Some sensors have global shutter instead, which makes it even more like DRAM: Conceptually each pixel has a capacitor and a photodiode, and a transistor connecting the two, all of these transistors are connected in parallel and form the "global shutter signal".
Some sensors have faster ADCs and use one ADC for a bunch of columns, which has been claimed as the source of column-banding in some sensors (unclear if correct).
[1] Sensors that are intended for both photo and video typically support things like pixel binning, where the sensor itself averages e.g. 2x2 blocks of pixels internally. A lower quality alternative is line skipping, where the sensor is told to only read out every nth line, thus reducing resolution considerably. The higher quality alternative is "full-sensor readout", i.e. the camera reads all pixels and downsamples the image to the video resolution. I believe some (announced?) sensors can do this in the sensor itself now.
Note: A lot of this is "somewhat informed speculation" on my part, because image sensor manufacturers tend to be very secretive of their sensor's details.
12- or 16-bit greyscale is common, with multiple channels for hyperspectral data. But since it can also store 32-bit data, floats, and complex numbers as well as rationals, it can be used as a container for pretty much anything you want to throw at it.
Regarding RAW. It's often used with colour CCDs with various types of CFA, like Bayer or CMY. It might have a higher bit depth, but it's still basically RGB but spatially separated and stored as greyscale. You could maybe feed it directly to your ML, but it's more common to filter it to create RGB data retaining the bit depth but at the expense of low pass filtering to remove aliasing artefacts. Or keep the separation to keep the high frequency components; really depends upon what information you want to extract.
I used to work on on of the larger imaging tools, supporting over 150 scientific file formats. The vast majority, over 80%, were using TIFF as a container. The next most popular was HDF5. FITS was not something I saw commonly, and we were getting images from researchers all over the world.
All I ask is that you share your findings with me and don’t redistribute the image data set without confirming with me.
We have a server with a 24TB NAS. If you send me your ~/.ssh/id_rsa.pub key, I can add you to it and you can upload straight to the NAS. Would that work?
I have an event to go to today, but if you hop into our ML discord server (https://github.com/shawwn/tpunicorn#ml-community) and DM me (I'm shawn), we can figure out the details. Or email me (shawnpresser@gmail.com).
Thanks so much! This is exactly what I had in mind when I was writing my comment. I think it would be straightforward to extend StyleGAN to synthesize full spectrum data. And the results would look pretty darn cool.
Sometimes a CCD bit was stuck, so we would process around that, etc.
The terms "HDR" and "photo" are not commonly used.
The Perkin-Elmer military system has fortran source, so all the file formats are documented there (if you can get access), as well as a minimal Scottish university system.
That’s one and a half billion astronomical units. The star in question is twice the sun’s mass, and, I guess, not too dissimilar in size. If so, if you had a camera that could take a 1,000,000,000 by 1,000,000,000 pixel photo of our sun from the earth and pointed it at this star, that star would fill a single pixel (Likely a few more more due to imaging imperfections, but those would mean the light gets smeared out)
It typically takes multiple ‘photos’ to even get a single of those CD observations in a frequency range (https://en.wikipedia.org/wiki/S2_(star)#S0–102: “At one-sixteenth the brightness of S0–2, S0–102 was not initially recognized because it required many more years of observations to distinguish it from its local infrared background”
It’s not as though conventional cameras operate on the exact same principles as our eyes, either. And that’s without even getting into the amount of “computational photography” performed on phones.
The Orion Nebula is a good target for grokking the difference. A long exposure photo with a DLSR (which will be blurry if you don’t have tracking) you’ll see lots of color. Through a pair of binoculars, you won’t although you will see the nebula.
No. Very likely not.
The photos may be of wavelengths of light that the human eye can't see, so scientists shift (and stretch/shrink) those into the visible spectrum.
That means the photos could contain something you can't see with the naked eye.
If you were to teleport there, you would (probably) see something, but the colors likely wouldn't be like in the photo.
This video has a pretty good explanation of what's going on: https://www.youtube.com/watch?v=WSG0MnmUsEY
It clarifies the motivation for extension/augmentation of human perception through technology, from microscopes to telescopes - and spectacles/glasses for that matter.
It also implies a continuation of the trend, where more and more of human perception will be mediated by technology, to benefit from advantages like accuracy, long-term memory/storage for data collection and statistics.
I guess augmented/virtual reality is part of it, where we can now perceive and experience a fully technology-mediated world, both real and imaginary. I picture sci-fi possibilities, like being able to "zoom in" to see things at magnifications beyond human biological limits - all controlled by thoughts.
Carbon based life at the third planet of our nearest G2V star still think they are the reference of the universe. They continue to measure starts without taking into account they are not alone.
And worst, they still jam the radio spectrum with nonsense TV commercials. We Alpha-Centaurians have have the worst neighbors in the known universe.
Just wait until they see what we're like when we get there.
Does this roughly mean, things are "sped up" in S62 from our point of view, if we could observe some activity on that star?
Simpler Sci without the Fi, but still incredible to lay people, is that earth’s gravity and the movement of the satellites cause time dilation that’s accounted for in GPS satellite clocks and the receiver clocks. It’s amazing how much the Special Relativity and General Relativity influence our daily lives.
See: The Wikipedia entry on GPS.
Time go faster at the top of a building compared to the bottom.
https://wtamu.edu/~cbaird/sq/2013/06/24/does-time-go-faster-...
I mean aside from the obvious one of it being an underlying theory for how the universe works and without it a lot of stuff would break it is really not that huge a part of most people’s lives. Sure, the GPS example is a fun one to bring up, but other than that there’s just a few things that we interact with that actually have a noticeable effect due to relativity, like some of the very characteristic properties of heavier metals or the design of particle accelerators, which many people used to have in their house until recently. And I guess you could go out and look at Einstein’s cross. But other than that it really doesn’t affect us that much.
tl;dr we perceive gps satellites clock ticks faster due to lower gravity (+46us/day), but slower due to motion (-7us/day).
You spoiled the movie.
Damn you. Damn you all to hell!
But time here also appears to pass slower to them (an observer there)!
Do we have to remember that the people we communicate with have different experiences of time?
Gender identity, sexual orientation, native language. Temporal perception?
Honestly it doesn’t seem hard to overcome. But I do love the idea of shipping off a problem and having it done 20% faster.
But wait, aren’t they 20% farther along in evolutionary terms too? So isn’t that like a multimillion year advantage?
This is already true on Earth. Different people process information at different speeds. Think about when you're talking to someone who is elderly. Do you slow down a bit so they have a chance to keep up?
I do think this thought experiment is a bit different though. In the sense that everyone orbiting S62 is faster than us, by a considerable margin. There will still be individual variances of course but the baseline moves. It’s not just a way you adapt to an individual but to an entire group of people, based on properties of their location.
I highly recommend it.
We can't, that's the whole point of relativity.
Communicating "instantly" would be a paradox.
Remember there is no absolute reference to which speeds are measured, aka. a "luminiferous aether". Its existence was disproved in the 19th century.
So Earthers are slow for observers on that star, but inhabitants of that star are also slow for Earthers; because speed is relative. Hence the name relativity.
And the reason it doesn't result in a paradox with light-speed communication is that the increasing (resp. decreasing) latency between the two account for the increasing (resp. decreasing) difference of time caused by this discrepancy of an object speeding up away from (resp. toward) the other.
There is an awesome article on wikipedia that describes it more. Totally blew my mind.
https://en.wikipedia.org/wiki/Relativity_of_simultaneity
As an aside, I’ve found this to be a helpful way to visualise data flowing through distributed systems...
It doesn't; phys.org is way off in their math (if they even bothered to check the math).
60 minutes, 11 seconds on earth would be more like it.
It will be hard to imagine if you try to retain the concept of some universal clock. The important thing is that if you actually traveled from one to the other that during your accelerations time would warp around you so as to perfectly make both sides local clocks correct.
This is the core concept of special relativity from which the rest is derived, neither of us is special in how our environment behaves. Whether you're on the spaceship traveling at 0.99c relative to earth or "at rest" (both are actually at rest but hopefully you know what I mean) everything feels the same as long as you are not accelerating.
And I also don't get your comment. Probably because I don't get relativity.
If we send a clock into space it will just tick away seconds (a unit designed by people). When it will return back to earth years later in my mind it just ticked away the same amount of time as it would have on earth.
What am I missing about relativity?
So when you travel away from the earth at the speed of light you can't see the rotarion of the earth. But when you move back to the earth you are still just as old as the people who were the same age as you when you left?
Imagine your clock is an LED, a light sensor, and a mirror. The “tick” of this clock is: the LED sends out a brief flash of light, which travels to the mirror, bounces off, and returns to the sensor.
If this clock is stationary relative to you, the time of that tick is the distance between the three components divided by the speed of light (c = d / t).
If it is moving relative to you, the light has to be at an angle, shining at where the mirror will be by the time the light gets there. This is a longer distance, and so it ticks more slowly from your perspective.
Every atom in your body, or in a clock, is held together by forces that behave like the light in the example clock.
Give two people clocks and have them move relative to each other, and both think the other is slow. This leads to the “twins paradox”, and while I can say the answer involves acceleration, I don’t fully intuit it and can’t help you with it.
Imagine the same volumetric difference exists in 3d space, but the different regions are not hotter/colder, but time goes faster/slower.
So You get two identical clocks, showing the same time, and move one of them into a “slow time” region (which would be a star moving very fast (8% of lightspeed). Let some time pass, then re-join the two clocks.
Since they spent some time in regions with different “speed of time” they’ll show a different time.
I might be wrong though, I’m not a professional.
The track is divided into lanes and each player is set backwards based on their lane by a fixed distance, despite the fact the finish line is in the same position. This is because of the curvature of the track - if everyone started at the same "line" across all lanes, the runners at the outer lanes would be running a further distance than those on the inner lanes!
Gravity does the same thing to time itself. The curvature is not of a track but of spacetime.
In Gravity, the main character starts at an inner lane and his daughter at an outer one - but the starting line is the same across all lanes. Gravity bends spacetime, such that the inner lane is shorter than the outer lane (in terms of distance in time). So when they ultimately arrive at the finish line, the daughter has traversed a longer path in the time dimension than her father.
The classic example is a clock of light ticking between two mirrors. If you are moving with that clock it is ticking at the speed of light. If I am in a frame of reference where the clock is moving perpendicular to the light tick's path, the light will have a greater distance to cover. [1] Since the speed is fixed to me, this tick is slower.
1. https://upload.wikimedia.org/wikipedia/commons/thumb/8/8e/Ti...
- https://www.youtube.com/watch?v=Bg9MVRQYmBQ
- https://www.youtube.com/watch?v=0iJZ_QGMLD0
(Although the time dilation in Interstellar is due to gravity, not high-speed travel.)
First, like others mentioned, they are way off in the effect size, for this kind of time dilation you need 80% the speed of light, not 8%.
Second, when looking at time dilation caused by velocity, it is always necessary to say who observes what since observers that move relative to each other won't agree on which clock runs at what speed. If the star moved at 80% of the speed of light, someone on that star would say "When a 100 minutes pass here, only 60 minutes pass on Earth" while an observer on Earth would say "When 100 minutes pass here, only 60 minutes pass on that star". So both observers would say that the other's clock is running slower than their own.
This answers a part of your last question - time dilation always makes clocks appear to tick slower than your clock if they move relative to you.
There are other effects that can make things appear "sped up", there's all kind of odd things happening when you go to high relativistic speeds ...
Interestlingly, the universe does have a preferred velocity (and thus a preferred inertial frame). It's the speed and direction that makes the cosmic background radiation not have a dipole.
https://astronomy.swin.edu.au/cosmos/c/Cosmic+Microwave+Back...
When they say "300,000 years after the big bang" how do they count that, is that seconds in some periodic movement inside matter or radiation?
Only after the universe became transparent did these photons become free, and since they were produced roughly homogenously in that soup there are everywhere in the same quanitity: a background radiation.
Since they were not produced in a localized event, they won't have a center. But since they're everywhere, they are a sort of absolute reference for how fast you're going (actually that's a new and interesting idea for me too, pretty neat).
What you’re asking is analogous to asking where the center of the Earth is on a map of the surface, and arguing it must exist because of how things on the horizon change when you move.
`Clocks slow down when they move in relation to you`
So to the "stationary" person, the clock of the person who zoomed off would be behind. But since it's relative, to the "zoomer" the stationary person went out and back. So then to the zoomer the stationary person's watch would be slower.
But which one is it? Do they end up showing the same time?
This is a famous paradox, see here for a full discussion/resolution: https://en.wikipedia.org/wiki/Twin_paradox
The recognition that there are consequences to our understanding of time if the speed of light is constant in every reference frame was earth shattering in the science community a century ago.
I don't know the details of what it would do if it was moving merely very fast, but curiously if it was fast enough, I'm talking unbelievably overwhelmingly fast, it would probably go right through without interacting. Why? Well, if you whiz through the electromagnetic fields of all the atoms in the earth fast enough, the forces won't have any time to transfer momentum one way or the other.
That is, in order for something to have this immense energy in our frame of reference, that something (or Earth) would have to get that energy somewhere. What I'm asking, essentially, is how likely is it that such conditions would exist at some point?
Yet sun sails work, despite being micrometers thick and interacting with particles going very close to c (from the sail's PoV).
If I’ve done my sums right, your example would have about 30 times the kinetic energy of that baseball, assuming the same mass.
Say the star was our sun, with a peak frequency at ~525nm. For reference, that's a good solid green, like that of fresh wet grass. If the star were moving away from you at 0.08c, then the color would redshift down to 569nm, a nice pale lime. If the star were moving toward you, then it would blueshift up to 481nm, an ultramarine blue. You can see the colors by wavelength here:
http://pages.cs.wisc.edu/~yetkin/code/wavelength_to_rgb/wave...
The reality seems more complicated because the star speeds up at the closest approach. When it speeds up, it is subject to time dilation. Time slows down more as it speeds up, and so any electromagnetic waves emitted by the body will have a lower frequency.
The effect of the speed up is not separable from the fact that it has dunked deeper into the gravitational field of the black hole, which also contributes time dilation.
> If you shine a beam of light into the sky, the light doesn't slow down, but gravity does take away some of its energy.
The red shift that we see is purely a time dilation effect. So that is to say, if there were, say, a 101.5 Mhz radio station on that star, we would see that at a lower Mhz figure purely due to the oscillator of that station appearing to be slower due to time dilation. Someone riding that star, clapping their hands once per second might look like they are clapping once every 1.2 seconds.
The beam of light which is conveying to us the events from a source cannot alter the frequency of those events, even if it changes speed along the way. If we see 1000 events per second, then it means the source is generating 1000 events per second, according to our frame of reference. It cannot be that the source is generating 1200, but then the light somehow subtracts from that due to losing energy while escaping gravity.
This is not true; or at least not that simple.
Under general relativity, the speed of light is c only locally. A remote observer can see a slowed down light.
It doesn't make sense that light could be bent by gravity, but not slowed down; and then there is the business of light not being able to escape from black holes.
https://physics.stackexchange.com/questions/59502/does-gravi...
I think I've read something about how the Milky Way's central black hole is unusually quiet, and speculation whether that was a prerequisite for life to develop.
Not the near future, no. Gravitational radiation is probably the only factor eroding its orbit, and it's a very small factor indeed.
You might see a merger between Andromeda & the Milky Way first!
It wouldn't seem so. The distance of closest approach to the hole is still 215 times the hole's horizon radius. The star's orbit will, over a very long period, decay due to emission of gravitational waves, so eventually it will fall into the hole, but not any time soon.
Still in the long-term, yes it probably will be eaten up. After all the galaxy's black hole must have fed on stars in order to reach the huge mass that it has now.
These stars are orbiting black holes, so they aren't traveling linearly to the distance end of the universe.
As for the time end of the universe, nobody knows for sure how the universe will come to an end. But if these objects are very hot due to their speed, then perhaps they will live a bit longer than others, unless they explode before then :)
Time. After entropy has had it's way, might there be some age-deferred stars zooming around?
Personally, this is one of my favorite Wikipedia articles. People talk about having a larger perspective, but this page outlines the extreme limits to that.
https://en.m.wikipedia.org/wiki/The_World_at_the_End_of_Time
> it visibly warps spacetime
The explanation for this part of the title was completely missing from the original article. They _might_ have been talking about the red shift?
So where did they get '100 minutes'?
I'm not sure what affect the black hole itself would have, maybe that makes a difference?
edit: 60.2, forgot to square the ratio.
It's phys.org. Don't expect them to actually check the math. They're way off.
> I'm not sure what affect the black hole itself would have, maybe that makes a difference?
No, gravitational time dilation due to altitude above the hole is negligible for this case; even the distance of closest approach is still 215 times the horizon radius of the hole.
WA for the Lorentz factor math because I'm lazy: https://www.wolframalpha.com/input/?i=sqrt%281+-+x%5E2%29+%3...
That said, given the time dilation, one wonders if LIGO could pull out the orbit from enough samples.
Is there a particular group associated with it these days? Back in the day it was hot rodders who were talking about fast cars. I wonder what the linguistic definition of a colloquialism's lifetime is, or if there even is one.
I’m not sure where you’re from, but this is just simply not correct. I have never been in that group and I know lots of people who regularly use that phrase. It’s a fundamental colloquialism.
Abstract theoretical concepts do not exist outside sectarian consensus.
This phrase is equivalent of saying like 'numbers became longer' or similar nonsense.
Also it would be nice to see any non-interpreted physical processes which involves space-time.
Thank you.
Two examples in this thread? Depending on the meaning of “non-interpreted”
> satellites cause time dilation that’s accounted for in GPS satellite clocks and the receiver clocks
And
> its speed approaches 8% of the speed of light. That's so fast that time dilation comes into play
Literally. Not being interpreted to support or confirm a current theory.
The abstract system of two clocks and an observer is just nonsense, since the first time it was introduced by Einstein. Abstractions put together to form another abstraction with supposed properties.
Any two clocks, bring man-made devices to support an abstraction of the mind, are completely unrelated instead of measuring the same phenomena.
Time dilation is just an error of measurement and of confirmation bias.
I am still looking for an actual experiment and at least one real process.
That speed varies by altitude in a very consistent way, and all the GPS satellites are showing the same clock skew of half a part per billion.
How is that measurement error or confirmation bias?
You could buy two atomic clocks yourself and watch how they differ based on altitude. They're definitely not "completely unrelated".
Again, this is a man-made device being affected by gravity, not time.
But what's the difference between every physical process slowing down, versus time dilation? Unless you're arguing that somehow only clocks slow down, and not other things?
How about muons? Are muons manmade?
If we observe that muons live longer before decaying if they take one path instead of another, does it make sense to say that time is being dilated?
https://en.wikipedia.org/wiki/Experimental_testing_of_time_d...
> Time dilation as predicted by special relativity is often verified by means of particle lifetime experiments. According to special relativity, the rate of a clock C traveling between two synchronized laboratory clocks A and B, as seen by a laboratory observer, is slowed relative to the laboratory clock rates. Since any periodic process can be considered a clock, the lifetimes of unstable particles such as muons must also be affected, so that moving muons should have a longer lifetime than resting ones. A variety of experiments confirming this effect have been performed both in the atmosphere and in particle accelerators.
Everything which follow the famous two lighting and a train thought experiment is simply logially flawed. Full of type errors.
Time as we know it, which presumably could accelerate and what not does not objectively exist, exactly and precisely the way numbers does not exit outside one's mind. Relations are, numbers not. Processes are, time isn't.
This is how I hacked Einstein. Why not?
Do you have any objection to the output of the equations matching reality, or do you just object to how we interpret the equations? Because the former is physics, and the latter is philosophy.
It is useless to argue on HN. I have literally 5 or 6 accounts banned for attacking a textbook ideas. It is easy to trace them all using HN backend.
Most of current HN crowd assume that I am some flat earth anti 5G lunatic, while I have background in philosophy, and down to earth physics way above that of downvoters.
Then don’t.
> I have background in philosophy,
I have an A-Level in philosophy, but it’s a terrible grade and I don’t get to make up for that in philosophical discussions by waving around my Software Engineering degree.
> and down to earth physics way above that of downvoters.
That choice of phrase alone will make you look like a nut. Would you care to rephrase that, with specifics? Do you work professionally with aerodynamic simulations, for example? Or perhaps you want tell us about the video game engine whose physics model you coded?
Observable distortion of trajectories of photons by a massive body does not involve any time.
He's not arguing that time doesn't exist.
With Higher or lower abstraction instead?
Does it really exist? Maybe, we don't know (Symmetries and space and time are one of the things we could have right today as opposed to the standard model which is fairly likely to not stand the test of time), but who are we to judge.