31 ms·
Fastest star ever seen is moving at 8% the speed of light
- sparrish 6y agoThat's not a star... that's a starship! <grin>
- Arnavion 6y agoBlogspam (but with worse editing) of https://phys.org/news/2020-08-fastest-star.html https://phys.org/news/2020-08-fastest-star.html
- mmastrac 6y agoThanks - this is much better. > 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?
- soulofmischief 6y ago> For years, S2 was thought to be the closest star to SgrA, but then S62 was discovered. As a team recently discovered, it's a star about twice as massive as the sun that orbits the black hole every 10 years. By their calculations, at the closest approach, its speed approaches 8% of the speed of light. That's so fast that time dilation comes into play. An hour at S62 would last about 100 Earth minutes.
- Dylan16807 6y agoBut time dilation at 8% of light speed is less than half a percent. The so-called "blogspam" has that part much more right: "At eight percent lightspeed, the time dilation effect for S62 just barely becomes noticeable" So where did they get '100 minutes'? I'm not sure what affect the black hole itself would have, maybe that makes a difference?
- soulofmischief 6y agoA back of the napkin calculation says 60m should be about 62.5m at that velocity. I'm not sure where that came from either. edit: 60.2, forgot to square the ratio.
- Dylan16807 6y agoIf you got a 2.5 minute difference, did you forget to square the .08? My napkin says that 60 / sqrt(1 - .08^2) is 60.2
- soulofmischief 6y agoI sure did forget, thanks for the catch.
- pdonis 6y ago> where did they get '100 minutes'? 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.
- Arnavion 6y agoThey got 100 minutes by using 80% of the speed of light instead of 8%. Oops. WA for the Lorentz factor math because I'm lazy: https://www.wolframalpha.com/input/?i=sqrt%281+-+x%5E2%29+%3D+60+%2F+100%2C+solve+for+x https://www.wolframalpha.com/input/?i=sqrt%281+-+x%5E2%29+%3...
- qubex 6y agoAt 8% of c time dilation & length contraction are about 0.3%. That’s definitely measurable, but whoever wrote this article clearly calculated values for 80% of c rather than 8%.
- deleted 6y ago[deleted]
- ChuckMcM 6y agoI chuckled at the retro colloquialism "thats booking it". Which was current in probably the late 70's early 80s of the last century. That said, given the time dilation, one wonders if LIGO could pull out the orbit from enough samples.
- hellofunk 6y agoI hear that phrase still today , often enough that I’d consider it current.
- ChuckMcM 6y agoWow, that's wicked cool :-) 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.
- cryptoz 6y agoI say both wicked cool and booking it, FWIW. Mid-30s and not sure what group I might be associated with. I guess some people would call me a hipster maybe. Haven't owned a car yet.
- hellofunk 6y ago> Back in the day it was hot rodders who were talking about fast cars. 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.
- stevenpetryk 6y agoIt's interesting to imagine that there's possibly other life in the galaxy who are also interested in this star, and in SgrA* in general.
- monkeycantype 6y agoSo if Copernicus and Einstein were drinking coffee with Galileo and Hawking on a little planet orbiting this star, trying to formulate an Alpha Sagittaricentric model of the galaxy, how much would Einstein and Hawking be contributing to the conversation? How important is relativity to explaining what they would be observing of the light from other stars?
- pirocks 6y agoWell for starters colours would be all weird.
- saagarjha 6y agoNot hugely.
- BurningFrog 6y agoRelativity only matters at very high relative speeds, which hardly exist inside the galaxy.
- daveFNbuck 6y agoIs 8% of the speed of light not a very high relative speed?
- mehrdadn 6y ago[Layman here] The Lorentz factor is 1/sqrt(1-v^2/c^2) = 1/sqrt(1-0.08^2) = 100.3%, so dilation effects would be obviously measurable but not particularly huge (0.3%).
- deleted 6y ago[deleted]
- 0xFFC 6y agoOne question, foes it exists outside of the galaxy?
- perl4ever 6y agoI'm curious - is this star likely to be "eaten" in the near future, and when something like that happens, could it potentially create a dangerous gamma ray burst or something? 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.
- networkimprov 6y agoI gather you're asking about the possibility of a "local" Quasar event -- formation of a large accretion disk around SgrA*. 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!
- pdonis 6y ago> is this star likely to be "eaten" in the near future 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.
- perl4ever 6y agoWell, sure, if you consider just the two objects, but I would think the neighborhood is dense enough that statistically something else might have a close encounter and change the orbit.
- spuz 6y agoProbably not. The star passes closer to Sgr A* than any other at 16 AU - about the distance between the Sun and Uranus - but that still puts it a long way from the black hole's event horizon. Despite its huge mass, Sgr A*'s Schwarzchild radius is only 0.08 AU. 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. https://en.m.wikipedia.org/wiki/S62_(star) https://en.m.wikipedia.org/wiki/S62_(star)
- johndoe42377 6y ago> spacetime Abstract theoretical concepts do not exist outside sectarian consensus. This phrase is equivalent of saying like 'numbers became longer' or similar nonsense.
- johndoe42377 6y agoCould any downvoters please provide information about any actual experiment which proves existence of space-time being of different kind than existence of a number. Also it would be nice to see any non-interpreted physical processes which involves space-time. Thank you.
- nuclearnice1 6y ago> any non-interpreted physical processes which involves space-time. 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
- johndoe42377 6y ago> meaning of “non-interpreted” 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.
- Dylan16807 6y agoThese are clocks with an extremely consistent speed, varying less than one part per trillion. 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".
- brainless 6y agoI find it really fascinating to think that when 60 minutes pass on star S62, on Earth 100 minutes would have passed in the same duration. This is Sci-Fi territory in my mind. I am having all sorts of difficulty imagining some implications of this. Does this roughly mean, things are "sped up" in S62 from our point of view, if we could observe some activity on that star?
- wtmt 6y ago> This is Sci-Fi territory in my mind. 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.
- spyder 6y agoYes: 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-at-the-top-of-a-building-compared-to-the-bottom/ https://wtamu.edu/~cbaird/sq/2013/06/24/does-time-go-faster-...
- saagarjha 6y agoWell, it’s that and also their speed, the effects of which are predicted by general and special relativity respectively.
- saagarjha 6y ago> It’s amazing how much the Special Relativity and General Relativity influence our daily lives. 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.
- Karupan 6y agoIt's funny how every time I read an astronomy headline mention the word "visible", my brain immediately interprets it as a conventional photograph and is slightly disappointed when there isn't one.
- mulmen 6y agoHah, thank you for summarizing this so well. I never really connected the dots on “visible” = “can be observed”.
- redis_mlc 6y agoVirtually no distant astronomical image is a normal photo that corresponds to what the human eye would see. 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.
- sillysaurusx 6y agoWhich file formats did you use? 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.)
- pdonis 6y agoThe article's title is somewhat misleading. The warping of spacetime that this star is making visible is not the warping due to the star itself; it is the warping due to the huge black hole at the center of our galaxy that the star is orbiting.
- pdonis 6y agoThe actual preprint on arxiv.org is here: https://arxiv.org/abs/2002.02341 https://arxiv.org/abs/2002.02341
- tus88 6y agoIt probably emanates gravitational waves too.
- m0zg 6y agoSpeaking of moving fast, is there anything in physics that limits how fast things are moving in space? I don't mean the limit of speed (that is already known) but realistically, how likely is there to exist, say, a tiny, fist-sized asteroid moving at a slightly sub-luminal speed? Say, 0.9997C in our frame of reference? And if such a thing were to exist, what would the consequences of it colliding with the Earth be? For the reference, an US quarter coin traveling at that speed has relativistic kinetic energy of 4.85MT TNT. We obviously wouldn't be able to detect an object moving this fast, but how likely is it to be out there?
- whatshisface 6y agoThere is always a reference frame where the rock isn't moving - and we all agree something can stay still, so there's nothing in physics preventing it from going as close to the speed of light as you want. 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.
- m0zg 6y agoYes, I understand that, that's why I'm asking not if such a thing is _possible_ but whether it is even remotely _likely to exist_, given what we know about the universe, how galaxies and stars came to exist, etc. 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?
- formerly_proven 6y ago> 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. Yet sun sails work, despite being micrometers thick and interacting with particles going very close to c (from the sail's PoV).
- ssijak 6y ago8% speed of light relative to what?
- bbarnett 6y agoI think you are missing the key point here. This is wan-to, clearly.... https://en.m.wikipedia.org/wiki/The_World_at_the_End_of_Time https://en.m.wikipedia.org/wiki/The_World_at_the_End_of_Time
- snoopen 6y agoCame here to ask exactly this. Not knowing much about relativity leaves me wondering if this is actually significant?
- runeks 6y agoRelative to the observer.
- TheGallopedHigh 6y agoRelative to the speed of Light. Because that is constant irrespective of the frame of reference
- zodiac 6y agoYour second sentence is true, but the first one doesn't make sense. A car travels at about 0.000001% of the speed of light, yet when we measure car speeds, they depend on the frame of reference.
- rini17 6y agoThere are surely red/yellow dwarf stars even closer to the black hole (beyond our observational capability). The skies on their planets would be fascinating (but hostile to life).
- rsecora 6y agoAn observer near Sagittarius A* at the star S62 has just published a report about us moving at 8% of the speed of light.
- Luc 6y agoUs and every other star they observe. Curious that.
- pbhjpbhj 6y ago"S62.4 News - this just in, proximate spatial anomaly gives some stars unprecedented redshift; could wormhole be to blame?" /fiction
- rsecora 6y agoAlpha Centauri Herald 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.
- ethbro 6y ago> 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.
- bargle0 6y agoThey won’t let that happen, but they’re probably not worried that we’ll even make an attempt.
- LanceH 6y agoTo be fair, they haven't seen Tiger King yet. That should smooth things over.
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- amelius 6y agoRelative to what?
- AnIdiotOnTheNet 6y agoUs, obviously. How else would we measure relative velocities?
- mrfusion 6y agoI wonder if we could do a slingshot maneuver around this planet.
- P-NP 6y agoBut what is the fastest known UNBOUND star that does NOT orbit a black hole? As of November 2019, it was S5-HVS1. Its speed is over 1,700 km/s or 1,056 mi/s. That's about 0.57% of light speed. S5-HVS1 will be flicked out of the Milky Way. The previous record-holder was US708, a white dwarf travelling at 1,200 km/s or 746 mi/s.
- WarOnPrivacy 6y agoAt the end of the universe, will the remaining stars will be the ones that were traveling the fastest?
- raducu 6y agoNo, the ones formed the last and the smallest red dwarfs.
- sushshshsh 6y agoDo you mean at the time end, or at the distance end? 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 :)
- WarOnPrivacy 6y ago>Do you mean at the time end, or at the distance end? Time. After entropy has had it's way, might there be some age-deferred stars zooming around?
- ColanR 6y agoI think they're just speeding towards the end of time faster than the rest of us.
- Balgair 6y agoAside: Here is a good 'timeline' of a few proposed futures for our universe: https://en.wikipedia.org/wiki/Timeline_of_the_far_future https://en.wikipedia.org/wiki/Timeline_of_the_far_future 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.
- Balgair 6y agoIf you were to look at this star in it's peak velocity relative to a stationary observer, you would see a pretty big shift in it's color! 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/wavelength.html http://pages.cs.wisc.edu/~yetkin/code/wavelength_to_rgb/wave...
- kazinator 6y ago> 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. As a result, a beam of light becomes redshifted as it climbs out of a gravitational well. 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-gravity-slow-the-speed-that-light-travels https://physics.stackexchange.com/questions/59502/does-gravi...
- kazinator 6y ago> In 2018, S2 made its closest approach to the black hole, giving us a chance to observe an effect of relativity known as gravitational redshift. 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.