[HN Gopher] Mysterious object is being dragged into the black ho...
___________________________________________________________________
Mysterious object is being dragged into the black hole at the Milky
Way's center
Author : thunderbong
Score : 161 points
Date : 2023-02-25 14:56 UTC (8 hours ago)
(HTM) web link (newsroom.ucla.edu)
(TXT) w3m dump (newsroom.ucla.edu)
| peteradio wrote:
| [flagged]
| ck2 wrote:
| 26,000 light years is a freaking long way away.
|
| The fact we can determine -anything- is mind blowing.
| taylorius wrote:
| A pallet piled high with unsold copies of Harry's blockbuster new
| book, "Spare"?
| hownottowrite wrote:
| It's literally just a cloud.
| jmbwell wrote:
| And The Cloud is just Someone Else's Stardust...
| mati365 wrote:
| Maybe it is smaller blackhole with gas around itself
| photochemsyn wrote:
| As NASA notes:
|
| > "...the Sun - in fact, our whole solar system - orbits around
| the center of the Milky Way Galaxy. We are moving at an average
| velocity of 828,000 km/hr. But even at that high rate, it still
| takes us about 230 million years to make one complete orbit
| around the Milky Way!"
|
| It takes a vast amount of energy for a stable orbiting body to
| reach the center of mass of the object it is orbiting around, for
| example that's why the small Parker Solar Probe (launched 2018)
| required the massive Delta 4 heavy rocket to provide the boost
| energy:
|
| https://www.youtube.com/watch?v=AlyuSwRSVHU
|
| So, 'dragged' isn't really the right way to think about it, is
| it? If two stars collided there must have been some massive
| energy input into the X7 object which accelerated it towards the
| black hole (it might instead have been accelerated away from the
| black hole, depending on the dynamics of the collision). Hence,
| 'it was shoved towards the black hole' is perhaps a more accurate
| view than 'it is being dragged by the black hole'.
| whatshisface wrote:
| It's not tugged towards the black hole in a straight line - the
| word "dragged" fits best if you interpret it like the drag on
| an airplane, something that's impeding the movement of the body
| and sucking energy away.
| photochemsyn wrote:
| I suppose a lot depends on the frame of reference, but if
| this came about from two stars colliding, it seems safe to
| assume these two stars were in relatively stable orbits
| around the galactic center. Those orbits were stable because
| of the dragging effect of the black hole, much like Earth's
| orbit is stable because of the dragging effect of the Sun.
|
| If the Earth smacked dead-on into another Earth orbiting in
| the opposite direction around the sun, I imagine most of the
| combined mass would start falling into the sun due to net
| loss of momentum, although jets of material might get
| accelerated further out into the solar system, as well as
| inwards. In that case 'dragged' might make more sense.
|
| The case for two stars seems more complicated, they start
| orbiting each other before merging, which could be a very
| energetic event if they were large enough, i.e. a 'merger-
| triggered core collapse supernova'.
| drewtato wrote:
| It would have been shoved backwards relative to the original
| orbit, perpendicular to the direction of the black hole.
|
| When you think of orbiting as "falling and missing
| continuously", the lowest-energy way to stop missing is to stop
| moving forward.
| proaralyst wrote:
| I just love the Delta's giant fireball at launch
| detrites wrote:
| Given the centre of the Milky Way is about 26000 light years
| away, shouldn't the title read "was" instead of "is being"?
|
| And if so, wouldn't adherence to HN's context policy require
| suffixing with a "(23977BC)"?
| jker wrote:
| Lighten up, Minkowski.
| andrewflnr wrote:
| HN title dates refer to the date of the article, not the event
| it covers. A 2019 article about an event on earth in 4000BC
| would still get (2019).
|
| But please do ignore the people confusing the delay in seeing
| distant events with relativistic simultaneity. It definitely
| did happen already in our reference frame. Just think of all
| astronomical events as being implicitly timestamped by
| observation time, not actual time. After all, distance is hard
| to measure in space, which means observation time is the more
| solid reference point.
| grey-area wrote:
| Only if you choose a parochial frame of reference like a small
| planet in the middle of nowhere instead of the centre of the
| galaxy.
| delecti wrote:
| There are no privileged reference frames. Choosing your own
| reference frame is perfectly valid.
| baq wrote:
| It happened there then. We see it happen here now. We couldn't
| have known about it in any other way, so for us it doesn't
| really matter that it was there then.
| kshacker wrote:
| May be it did not happen. May be Doctor Who or Captain Picard
| or someone not only saved themselves but also pulled the
| object out. Until it is confirmed to be sucked in completely,
| jury is still out on this one
| ericrallen wrote:
| When will then be now?
| krapp wrote:
| Soon.
| jjulius wrote:
| When will soon be then?
| canadiantim wrote:
| Now.
| geerlingguy wrote:
| This sounds like an excurb1a video.
| ricksunny wrote:
| It's a brilliant reference to Spaceballs
|
| https://youtu.be/5drjr9PmTMA
| kryptiskt wrote:
| It's best to talk about it as if it's happening now. It is
| happening now from our perspective, and if we were to refer to
| it in past tense talking about its near future (in our past but
| in the object's future) would tie us up in grammatical knots
| instead of just being able to use future tense.
| wizofaus wrote:
| What if humans had traveled far enough away (say, a few light
| weeks) and sent back a signal that a catastrophic failure
| meant they would be dead for certain within days? Would we
| still describe and think of the event of their death being in
| the future?
| thethimble wrote:
| If you think about the speed of light as the speed of
| causality then it is happening "now" in the sense that its
| effect is perceptible to us now. This seems like a good
| definition of now.
|
| Grammar becomes complicated when relativity dictates that
| there's no universal ordering of events/timeline.
| leoqa wrote:
| I suppose there is a universal ordering as a function of
| your position in the universe. Given that it's impossible
| for an observer to be in two places where relativity
| differs, that simplifies to "there is exactly one universal
| ordering of events for each observer"
| thethimble wrote:
| Not so "universal" if it's per-observer, right?
| wizzwizz4 wrote:
| There's a universal partial order of events. If
| something's in your future light cone, or your past light
| cone, that fact is independent of the observer. For the
| things that are not dependent on your present, and do not
| affect your present, different observers can have
| different understandings of the order.
| startupsfail wrote:
| Statements "something is in your future" and "that fact
| is independent of the observer" seem incompatible. When
| you are saying "your", you are talking about that
| particular observer, so you are negating the
| "independent" part.
| kryptiskt wrote:
| An example: You on Earth see events X and Y happening at
| Alpha Centauri and Proxima Centauri respectively. If the
| observers at Proxima Centauri didn't see event X
| happening at Alpha Centauri before Y happened there, and
| the observers at Alpha Centauri didn't see Y happening at
| Proxima Centauri before X happened there. Then the events
| can be seen in either order by an external observer
| depending on where they are and how fast they move. If an
| observer at Alpha Centauri or Proxima Centauri did see
| the other event before their event happened, then they
| have a well defined order ('is inside the light cone').
| Retric wrote:
| Which isn't particularly meaningful when each location
| can agree on the ordering observed at the other
| locations.
| Retric wrote:
| It's dependent on a specified reference location not the
| existence of an observer at that location. Further you
| can compute these timelines for that location without
| physically being at that location.
|
| Thus given location X you can get a universally agreed
| upon ordering. Or alternatively you can devise locations
| from various sets of orderings. A related example might
| be using multiple audio recordings to determine when and
| where various shots were fired.
| startupsfail wrote:
| Reference location in where? In multiverse? But then
| again there is a dependency on having a correlation with
| something that can contain bits of information.
| photochemsyn wrote:
| Whose relativistic frame of reference? My relativistic frame of
| reference!
| karaterobot wrote:
| I think you've got tongue in cheek, so here's an upvote and a
| non-didactic reply.
| jrootabega wrote:
| Isn't it even more technically accurate to say that it hasn't
| happened yet, and actually won't ever happen, in our frame of
| reference?
| amluto wrote:
| No, it already happened in our frame of reference. Our frame
| of reference, in special relativity, is a spacelike slice
| through the universe, "now" is what we would conventionally
| think of as "now", and light moves at the speed of light.
|
| In general relativity, things get weird and frames are more
| of a local phenomenon, but as long as you stay away from the
| event horizon, it's not _that_ weird.
| xwdv wrote:
| The event has already happened, even though we cannot see it
| yet.
|
| There is no way to reach some state where you could still
| exist in a universe where the event hasn't happened. If you
| traveled at the speed of light to the event location, you
| would see it has already happened.
|
| Since the speed of light is the fastest possible movement,
| there is no way to arrive at the event location faster than
| that, any faster movement means you would be time traveling
| back into the past in attempt to reach the event before it
| happens.
|
| Any possible event that happens in our daily lives starts off
| with two possible states: happened or didn't happen. When one
| of those states is eliminated, the event status is resolved
| and reality is updated. Usually we see these updates occur
| damn near instantly. In this case, in this universe, the
| "didn't happen" state has been thoroughly eradicated. But at
| these distances, we don't see updates yet, but it has
| happened.
|
| Therefore, you can consider the event as having happened. It
| was... inevitable.
| jrootabega wrote:
| The object has been fully dragged across the event horizon
| into the black hole?
| anonymouskimmer wrote:
| > Since the speed of light is the fastest possible
| movement, there is no way to arrive at the event location
| faster than that, any faster movement means you would be
| time traveling back into the past in attempt to reach the
| event before it happens.
|
| I don't quite get the time travel bit. I've seen too many
| sci fi and fantasy shows where time is effectively frozen
| while supernatural entities move about. Other than the
| supernatural entities moving about, the instant is the same
| everywhere, it doesn't go back.
|
| And if I see an event at Alpha Centauri, and immediately
| teleport there, the light wave is still at Earth. I haven't
| traveled back in time to the origination of the light wave
| at Alpha Centauri. And my light wave will not reach Earth
| until another ~4.3 years has passed after the first light
| wave that prompted my journey to Alpha Centauri. So the
| observer will not see anything unusual. I will not have
| rewritten the light pattern they saw.
|
| Also I think astronomers do see events which appear to be
| violations of causality, but are actually just
| gravitational distortions of the light traveling from an
| event. So interference with the travel of light from an
| event can't really be seen as traveling back in time.
| xwdv wrote:
| > I don't quite get the time travel bit. I've seen too
| many sci fi and fantasy shows where time is effectively
| frozen while supernatural entities move about. Other than
| the supernatural entities moving about, the instant is
| the same everywhere, it doesn't go back.
|
| Those representations are inaccurate.
|
| If time is truly frozen, that means photons should be
| frozen in place, unless photons are somehow exempt due to
| having no mass and thus no time.
|
| If the frozen photon theory is correct, you would have to
| see things by moving your eye into rays of light and
| letting photons hit your receptors and get consumed. But
| because these photons are being consumed and not
| replaced, you will leave pockets of darkness where your
| eyes will see no signal if you pass through there again.
|
| At normal everyday distances you will see everything
| frozen in place with this method. However, at long
| distances such as light years, moving into the light
| source will run its animation over time at the speed you
| are moving toward it. So you will see the event occur
| before your eyes right up until you reach the destination
| where the event has already occurred, and you can observe
| firsthand what we already knew to be true.
| anonymouskimmer wrote:
| > Those representations are inaccurate.
|
| Yes, I know Sci Fi and fantasy are inaccurate depictions
| of reality.
|
| > So you will see the event occur before your eyes right
| up until you reach the destination where the event has
| already occurred, and you can observe firsthand what we
| already knew to be true.
|
| I get this.
|
| I just don't get how moving faster than the speed of
| light (or causality) necessarily invokes literal time
| travel. And while I've read that physical scientists are
| amazed at how well mathematics model and predict reality,
| if this time travel is a result of the mathematics, then
| I need to be convinced that in this case the mathematics
| really are modeling reality.
| xwdv wrote:
| Look at it this way, let's say you're at the event site
| and seeing it happen right in front of you.
|
| Suddenly, some travelers arrive and say they also came to
| witness the event, but they came from light years away.
|
| How? The light of the event would have only traveled for
| a few light minutes, and no other type of information
| would travel faster than that. There's no way someone
| light years away would know about it yet.
|
| The only explanation, assuming they didn't perfectly
| predict the event, is that they time traveled. From your
| perspective they covered a distance of light years in the
| span of time between the event's start and you first
| meeting them.
| anonymouskimmer wrote:
| Sure. But assuming time is traveling the same for you,
| their origin point, and the photons going between the
| two, they won't suddenly appear when the event has just
| begun, even if they travel instantaneously. Because, as
| you say, the point at which they first saw the event had
| yet to receive the light image of the event.
|
| And if they do seem to suddenly appear much faster than
| you would believe possible, you suddenly know that you're
| at the bottom of a time-dilation gravity well (or the
| equivalent). Though you probably could have figured this
| out beforehand from the red-shift of the light traveling
| between the two points. Or you know that they observed
| the event from a closer point of view, instantaneously
| traveled to a most distant location to change clothes,
| and then traveled again to your location. Time travel is
| only one of at least three possibilities.
| haneul wrote:
| If you were to teleport to the appropriate space
| coordinates upon seeing the event, the event being in the
| past (since you are seeing the event with light delay),
| you would not arrive in time to see it up close.
|
| If you wanted to see it up close, you would have to
| travel into the past, since your teleportation would have
| to include a translation of time coordinates, not just of
| space coordinates.
|
| Also, although order of events is variable, causality is
| (I believe) currently assumed to be absolute, so while
| two observers can differ on which came first between
| events A and B, this is only possible if A and B's light
| (really, information) cones do not intersect such that
| one precedes the other causally.
|
| Suppose A does not intersect B by light cone, and you can
| instantly teleport. Then you can interact at A, teleport
| and interact at B, then immediate teleport everywhere in
| the universe, causally intertwining all frames before
| causality can physically propagate to those coordinates.
| Then you have time traveled to such an extent that I have
| no idea how the universe reconciles such a thing.
| anonymouskimmer wrote:
| It seems to me a bit like scattering a bunch of sand onto
| a still body of water. The sand hits simultaneously at
| all points, creating waves that interfere and reinforce
| each other. Why does the universe have to reconcile? Just
| let the waves do what they do and move on from that.
| anamexis wrote:
| Or you can consider the event as "inevitably will happen."
| Just as valid.
| willis936 wrote:
| "c" isn't "the speed of light" so much as "the speed of
| causality". Light just happens to be massless packets of energy
| that move at the speed of causality.
|
| For all intents and purposes this is happening in real time
| from our local frame of reference.
|
| https://youtu.be/msVuCEs8Ydo
| detrites wrote:
| So if sometime in the future, a pregnant human left Earth
| (say, through MuskTech's wormhole), and gave birth on a world
| orbiting Proxima Centauri, Earth's registrar shouldn't record
| it without adding an additional 4.3yrs?
|
| And when should the family back home celebrate?
|
| Defining the actual timing of events based on the presently
| available methods to perceive or communicate them seems odd
| if not also a bit impractical.
| delecti wrote:
| Coordinating events as precise as births in a
| multiplanetary society is already going to be inherently
| impractical.
|
| The family back home should celebrate when it's relevant.
| If there's a wormhole, then the kid can probably make a
| call through it, so they can call on their (self-perceived)
| birthday. If the wormhole is a one-way trip, then the
| people back home should wait an additional 4.3 years to
| celebrate, because they won't have any idea until then.
| ethanbond wrote:
| IMO better description is "c is the maximum speed of
| information"
|
| Quantum entanglement can create _causal_ effects much
| "faster" than c, but you cannot use such effects to transmit
| information still.
| jakeinspace wrote:
| This is a different situation from when one normally might
| use the phrase "correlation does not imply causation", but
| it applies here.
| jinwoo68 wrote:
| Measuring spin up of particle A is NOT a cause of measuring
| spin down of its entangled particle B.
| ethanbond wrote:
| Isn't waveform collapse at Location B caused by waveform
| collapse at Location A?
|
| (Maybe a stupid question, I've only a passing interest in
| this stuff)
| jinwoo68 wrote:
| My understanding is that when particles are entangled
| with each other, they must be described together with one
| wave function rather than one wave function for each of
| them. So once you measure particle A, the wave function
| collapses both for A and B.
| ethanbond wrote:
| Right. That... seems like causality to me.
| Filligree wrote:
| Location B will measure both up and down, but will only
| be able to communicate with the version of location A
| that measured the opposite value.
|
| There's no need for FTL if you accept MWI.
| codethief wrote:
| No, if you change reference frames (in the special
| relativistic sense), the direction of causality might be
| opposite, i.e. collapse at B might suddenly cause the
| collapse at A.
| ethanbond wrote:
| Well sure, but that's still causality.
| chrisfosterelli wrote:
| We are mixing up correlation and causation in this
| thread. In quantum entanglement you have a correlation,
| not causation.
|
| For example, if you go on a trip and bring your suitcase
| with you. You discover on opening it that you packed only
| one blue sock. You then gain the information that your
| other blue sock must be at home. You didn't "cause" your
| sock to appear at home at that moment, you simply gained
| that information from a correlation that you know must be
| true. The cause occurred when you were packing. In this
| case the correlation is entirely local though: you always
| had that information with you in your suitcase, you just
| didn't look at it until now.
|
| In quantum entanglement the cause and effect were the
| entanglement itself. When one of the particles is later
| observed, you're using correlation to decide what the
| other end is. The difference is that in quantum theory
| this correlation can be demonstrated to be non-local --
| the information wasn't with you the whole time and was
| only determined at the moment of observation. But you
| can't take any action based on it and the other side
| can't either as you have no way to know who caused the
| collapse. You can't cause any meaningful effect on the
| other end with the information you get from your
| observation or the act of your observation.
|
| If we are using "cause" in the colloquial sense then yes
| I see what you're saying, it "causes" it. But it's
| important to be specific with domain terms here because
| entanglement does not violate _causality_ , which has a
| specific definition.
| ethanbond wrote:
| Yeah this points to why I think _information_ is actually
| the salient feature.
|
| Thanks for taking the time to comment. How could I go
| about learning more about the specific definition of
| causality you're referring to here?
| chrisfosterelli wrote:
| The wikipedia page on causality is a good place to start
| for a clear overview, specifically the section on
| causality as a physical concept:
| https://en.m.wikipedia.org/wiki/Causality_(physics)
|
| As the wikipedia article touches on, there's not an
| agreed global definition and it can be used differently
| in multiple contexts (hence why it's important to be
| specific).
|
| This stack exchange answer gives a good list of
| terminology: https://physics.stackexchange.com/a/34675
|
| And this article puts a far more technical description on
| terms: https://www.mprl-
| series.mpg.de/media/proceedings/3/9/Proc3ch...
| codethief wrote:
| No, it's not. From our frame of reference (which, in General
| Relativistic terms, defines a coordinate system with a time
| coordinate) it still happened 26,000 years ago.
|
| If your friend tells you today about how they did X
| yesterday, would you also argue X happened today from your
| frame of reference?
| anamexis wrote:
| If you watch your friend do X right in front of you, would
| you argue it happened yesterday?
|
| They're both valid interpretations.
| Supermancho wrote:
| > If you watch your friend do X right in front of you,
| would you argue it happened yesterday?
|
| If that friend was 671 million miles away, I was say it
| happened yesterday. If it was a much smaller distance, I
| can intervene in the event because the relative effects
| do not prevent me from interacting.
|
| > They're both valid interpretations.
|
| That's true if you want to accept interpretation without
| restraint. I prefer consistent interpretations that are
| compatible with known physics. YMMV
| anamexis wrote:
| There are no consistent interpretations!
|
| The photon you're seeing that came from 671 million miles
| travelled to your eye instantly, from its "perspective."
| LawTalkingGuy wrote:
| You didn't watch them perform an act in front of you, you
| watched them on a remote viewing device (telescope,
| youtube video, etc) which was in front of you.
|
| And no, you wouldn't deny it happened yesterday. If you
| were watching a live event in front of you you'd have the
| ability to interact with it, such as by asking your
| friend to stop. If you're viewing something that already
| happened, you don't have that ability to interact.
|
| Quantum theory and relativity aren't tools to decrease
| our specificity and understanding of the universe so they
| shouldn't be used to justify "all interpretations are
| valid" type statements.
| anamexis wrote:
| A telescope isn't a remote viewing device, it's photons
| hitting my eyes just the same as if I were standing
| directly in front of whatever I'm observing.
|
| I'm not trying to do some new-agey "everything is valid"
| thing here. If I, like the photons, travelled from the
| source 671 million miles away to Earth at the speed of
| light, time would not have advanced for me at all. I
| would be telling you that what you are seeing is
| happening right this instant. And I would be right!
|
| And of course time on Earth has advanced considerably
| while I was traveling, from Earth's perspective. This is
| also true.
| LawTalkingGuy wrote:
| > A telescope isn't a remote viewing device, it's photons
| hitting my eyes _just the same as if_ I were standing
| directly in front of whatever I 'm observing.
|
| It is a remote viewing device because we're discussing
| using it to view remote events. And you're trying to say
| "just the same" despite that there are obviously some
| differences so it cannot be just the same. Try "somewhat
| analogously".
|
| > If I, like the photons, travelled from the source 671
| million miles away to Earth at the speed of light, time
| would not have advanced for me at all. I would be telling
| you that what you are seeing is happening right this
| instant. And I would be right!
|
| No, because it took you 1 hour to get here, and if you
| went back you wouldn't be there at the time you left, so
| in no way are the events simultaneous.
|
| You're only describing subjective experience - and
| someone who travelled much more slowly in stasis would
| have the same subjective experience despite their report
| of objective simultaneity being even more obviously
| incorrect.
| wolfendin wrote:
| This confuses the ability to access information about
| events with the process of accessing information about
| events.
|
| Things happen at the earliest possible moment I _could_
| know about them.
|
| I was able to get that information about my friend
| yesterday, I just didn't.
|
| I couldn't have learned about this 26,000 years ago.
| anonymouskimmer wrote:
| I kind of don't like this interpretation of events.
|
| The speed of causality varies depending on the speed of the
| causal particles and waves which propagate from an event. I
| was just reading an article on surviving nuclear detonations,
| and from those you have a few causal events propagating at
| different rates: the radiation, the shockwaves, the fallout.
|
| And if a tree falls in a forest with no one around, it does
| still make a sound.
| Maursault wrote:
| > And if a tree falls in a forest with no one around, it
| does still make a sound.
|
| I don't think you'll like the reason why. It was Bishop
| Berkeley[1], who gave his name to Berkeley CA, that
| originally posited and answered this question, and his
| answer was that God is always around and, thus, among other
| things, hears everything, so the falling tree makes a
| sound.
|
| [1] https://en.wikipedia.org/wiki/George_Berkeley#Contribut
| ions_...
| sidlls wrote:
| That's not the reason why. The reason why is that the
| falling tree disturbs particles in the atmosphere while
| it falls (which makes a sound) and when it hits the
| ground (which makes another sound--both from the
| vibration of the ground/air interface and through the
| earth itself).
| oceanplexian wrote:
| This is precisely what is happening.
|
| The whole philosophical debate is the most idiotic thing
| I have ever heard. Of course things happen even if a
| human doesn't observe it. Then they have to make up
| something about a magical religious figure hearing the
| tree. All I can think of is the Monty Python skit "..pray
| that there's intelligent life somewhere up in space,
| 'cause there's bugger all down here on Earth"
| andsoitis wrote:
| > God hears everything
|
| It is probably wrong to assume that God interfaces with
| the physical universe in the same way as us (and other
| living beings who perceive sound).
|
| They (God) may perceive vibrations of air particles in a
| way that we wouldn't call "sound".
|
| In fact, I'm pretty sure they have to otherwise they
| would be overwhelmed by all the noise they hear from
| everywhere all the time.
| p1mrx wrote:
| > I don't think you'll like [some dead guy's] reason why.
|
| The first person to ask a question doesn't have a
| monopoly on the answer.
| anonymouskimmer wrote:
| I'm fine with that reasoning; however from another point
| of view: The tree is a subject, too.
|
| For this particular instance, since the event is about
| 26,000 light years away, we could as easily say that it
| happened in 50,000 B.C., since that was the time on Earth
| when _our_ light traveled to meet _it_.
| muontraveller wrote:
| If God can hear the tree falling, then perhaps he's
| listening in a 4th dimension of spatial reality.
|
| All but a 3D place so we could avoid time dilation and
| experience other planets in real-time.
| Swizec wrote:
| The tree makes air move, but you need a subjective
| experience to turn that into sound.
| Sebb767 wrote:
| That depends on whether you define sound as air
| waves/vibration or the sensation of hearing. Definitions
| vary [1,2,3], which is why this philosophical question
| manages to get people talking past each other.
|
| [1] https://www.merriam-webster.com/dictionary/sound
|
| [2] https://en.m.wikipedia.org/wiki/Sound
|
| [3]
| https://dictionary.cambridge.org/dictionary/english/sound
| (note that "can be heard" != "is heard")
| sidlls wrote:
| Then it's not a philosophical question so much as about
| the meaning of "sound". And "debates" about semantics are
| about as uninteresting as it gets.
| mistermann wrote:
| > And "debates" about semantics are about as
| uninteresting as it gets.
|
| A 'fact' that is relative to the frame of reference of
| the observer.
| sidlls wrote:
| Nah, there's nothing less interesting and more irritating
| than bikeshedding of that sort. Nobody cares about some
| blowhard's attempt to generate pointless "debate" over
| hypotheticals and semantics.
| Sebb767 wrote:
| A lot of "philosophical" questions boil down to semantic
| debates, see the sleeping beauty problem for another one
| [1]. So we can get into a philosophical (or semantic?)
| debate about that, for a funny instance of recursion :-)
|
| But I agree with that those debates are quite
| uninteresting, so let's not do that.
|
| [1] https://en.wikipedia.org/wiki/Sleeping_Beauty_problem
| ctoth wrote:
| Did... Did this actually just happen for real?
|
| https://www.lesswrong.com/posts/a7n8GdKiAZRX86T5A/making-
| bel...
| anonymouskimmer wrote:
| I don't get why you're posting this in a surprised
| manner. Yes, these philosophical debates have been
| happening for many, many years (and when they do happen
| they often happen with famous philosophical questions
| such as the tree-forest-sound one). Yudkowsky wasn't
| making a novel philosophical discovery, he was just
| putting particular philosophical debates and meta-debates
| together into an essay.
| Sebb767 wrote:
| Well, I guess there's always https://xkcd.com/1053/
| Matumio wrote:
| > happening in real time
|
| Not sure about calling this "real time". If you actually
| wanted to do something about it (like saving the poor,
| mysterious object), then any help you send will face a
| completely different situation from what we see now.
| tiagod wrote:
| Imagine a world which is almost flat (but hilly), really
| big, and with a transparent atmosphere. We had extremely
| good telescopes, so from a big hill we could observe people
| a few thousands of km away, but we could only move very
| slowly.
|
| In the distance, there was another civilization that didn't
| have the technology to see us, or any other way to
| communicate with us. We also didn't have lasers or any
| other tech to send messages to them, other than travelling
| there (which would take some years), but we could see what
| was going there in almost real time.
|
| Wouldn't the same still apply, even without the limitations
| of the speed of light?
| tshaddox wrote:
| Okay, but that's also true if I hear about a house fire 50
| miles away. It's way too late for me to do anything to save
| anyone there.
| NegativeK wrote:
| Causality is definitely not simultaneity.
|
| And yes, the speed of light is defined by the speed of
| causality, but c is still, among other things, the speed of
| light.
| Sir_Liigmaz wrote:
| The idea of simultaneity kinda breaks down on those kind of
| scales
| nine_k wrote:
| It's called "spacetime" because space is inseparable from time.
| Any distance in space means a distance in time. Things
| happening "at the same time" are a convenient fiction
| applicable at short distances. Even things "happening in a
| particular sequence" is a fiction, if one events is not causing
| the other: what "happens first" depends on where you are
| looking from.
|
| Speaking about something beinng _N_ lightyears away from us
| just means both the distance in space and time. What we are
| seeing happening there and then is not from our past: it could
| not affect our past because the light from that event hadn 't
| arrived to us when and where our past was happening, and thus
| could not affect our local past. We see it happening "before"
| our past, but observers elsewhere may see it happening "at the
| same time" or "after" our past, in their frames of reference.
| analog31 wrote:
| This issue is raised whenever there's a discussion of things
| happening at a great distance. In my view, a convention of
| reporting the time when something is observed on earth, and
| maybe the distance if it's not commonly known, is a reasonable
| one. Anybody is free to convert the number to their preferred
| reference frame.
| babyshake wrote:
| It is always mind-blowing to remember that in the
| astronomical scale, it is impossible to know things that are
| happening right now or relatively recently by our standards
| unless there is information traveling faster than the speed
| of light, which is something that at this point remains
| purely in the realm of science fiction as far as we know.
| anyfoo wrote:
| It's even more mind-blowing to remember that on that scale,
| the concept of "things happening at the same time" does not
| exist, because the reference frames don't allow for it.
|
| That's so bizarre: Stand here, thing A happened before
| thing B. Stand over there, thing B happened before thing A.
| Stand at this other place, now they did happen at the same
| time, but only for you! Nobody's more right than the other.
| Universally, "same-timeness" (simultaneity) does not exist.
|
| So, by asking for:
|
| > to know things that are happening right now or relatively
| recently by our standards
|
| You're really only asking for your particular flavor of
| "right now or relatively recently".
| [deleted]
| EVa5I7bHFq9mnYK wrote:
| Where they stand does not matter. If those three
| observers do not move in relation one to another, they
| will see events in the same order.
| Sebb767 wrote:
| This is actually not true. Look at the following
| constellation:
|
| A--1--B--2--C
|
| Imagine 1 and 2 are satellites and observer B launches a
| rocket at both of them at the same time. From B's
| perspective, both satellites explode at the same time.
|
| A, however, will see 1 explode before 2. C, on the other
| hand, will see the reverse, that 2 explodes first.
|
| There's no right ordering here, just different reference
| frames.
| anyfoo wrote:
| You're right. I meant they are each standing in their own
| reference frame, so effectively they are moving with
| reference to each other, but I guess that wasn't entirely
| clear. For example: One observer is on Earth, the other
| on another planet outside the solar system.
| [deleted]
| andsoitis wrote:
| For this reason, I also don't see how we could ever travel
| at faster than light speeds because we wouldn't have the
| information that we won't crash into something at the other
| end.
| cronix wrote:
| Yes, but I think once we reach that point we'd also be
| sending out some sort of mapping probes to gather data so
| you know where obstructions are. And since lots of things
| don't just sit still, they'd have to be constantly
| reevaluated somehow. Maybe sensors sending out data of
| what lies ahead kind of like our GPS. It will be an
| interesting issue to solve if we make it that long. But
| looking at how we're doing in our infancy with "self
| driving," we quite a long ways off lol.
| themitigating wrote:
| A new conspiracy theory claims that the government or
| whatever is lying about the distance from the earth to the
| sun. I think for less intelligent people the size of the
| universe and its objects is too much to handle
| mistermann wrote:
| I think it could be argued that in certain specific
| scenarios, this shortcoming (in normal scenarios) can be
| advantageous, such as thinking outside the boundaries or
| constraints of a box, where the constraints happen to be
| incorrect but culturally axiomatic and are thus
| insurmountable for normal, "proper" thinking people.
|
| Having observed many thousands of discussions about
| "conspiracy theory" or "just wrong" (but the normal
| person can't explain _why_ it is wrong, in fact) topics,
| I am very confident in this belief. And now having also
| had some similar conversations with ChatGPT, which is
| able to overcome with ease many mistakes that humans
| make, yet cannot overcome others, I am even more
| convinced.
| themitigating wrote:
| Thinking outside the box sounds like coming up with new
| ways of doing things or being creative. I don't see how
| this is related to conspiracy theories, people are just
| mostly just hearing them from other people
| peyton wrote:
| Here's NASA misstating the distance between the Earth and
| the Sun: https://www.nasa.gov/sites/default/files/files/Y
| OSS_Act1.pdf
|
| Obviously the Earth's orbit is noncircular. Is that what
| you mean?
| themitigating wrote:
| This says the distance is 93m miles. That's about what
| the distance is
|
| I'm referring to people who think it's like a few
| thousand feet above the earth.
| andsoitis wrote:
| Misstatement is different from lying, no?
| labster wrote:
| At some astronomical scales numbers like this don't
| matter. Sure, if you're doing parallax calculations you
| need precise orbits, but most of the time you can assume
| p = 3.
| analog31 wrote:
| It's mind boggling for me too, and I even took special
| relativity in college. The only reassurance is that for
| now, it's not of too much practical importance. The
| limitation of traveling at the speed of light is not a
| technological barrier for us yet, likewise the posted speed
| limits are not a limitation when I'm on my bicycle.
| Aperocky wrote:
| The cone of causality establishes a present time for all events
| that _we_ are able to know.
|
| There are no universal time across the universe due to
| relativity, so the only time that make sense and can be
| determined with any degree of accuracy is _when it happened
| from our perspective_.
| mckirk wrote:
| Let's just say 'it will have been dragged' to be on the safe
| side either way.
| awb wrote:
| > about 26000 light years away
|
| _about_ makes this suggestion completely impractical
| detrites wrote:
| Alright, 26673 LY within 0.3% accuracy:
|
| https://www.aanda.org/articles/aa/abs/2019/05/aa35656-19/aa3.
| ..
|
| (So "24650BC" for... context.)
| awb wrote:
| 0.3% is +/- 80 years. So it's not 24650BC, it's
| 24570-24730BC. And the farther distance you go, the greater
| the uncertainty.
|
| And when measurements improve or are revised, everything
| would need to be recalculated. So, for posterity, it would
| be 24570-24730BC (2023 measurements).
|
| Or, 2023 is simpler.
| gpderetta wrote:
| That's litterally true for everything. Even something that's
| happening right in front of you has technically happened a few
| nanoseconds in the past.
|
| I do appreciate the HN joke though.
| pizza234 wrote:
| An astronomer on Reddit* says:
|
| > because the light we see is ~25k years old from the center of
| the galaxy, we are seeing it as it was 25k years ago. However,
| in astronomy we do not worry about this and instead just use
| the time at which the light reaches Earth- firstly there is
| just no way to know what is happening there literally now
|
| so in their view, it seems assuming the event as present is the
| norm.
|
| *:
| https://old.reddit.com/r/science/comments/11bk0u1/a_mysterio...
| chongli wrote:
| When you look at anything you are seeing what it looked like at
| least a few hundred picoseconds (very close to your face) to
| several nanoseconds (around the room you're in) in the past.
| The difference here is a matter of degree, not kind.
| bcbrown wrote:
| Light travels a foot per nanosecond, more or less. I believe
| this can be a real constraint in IC/motherboard designs with
| gigahertz+ clock speeds.
| golergka wrote:
| Not really. Time is relative, not absolute.
| antihero wrote:
| [flagged]
| bluebluetimes wrote:
| Is this a star that's collapsing into the massive black hole as
| it's 50x size of earth? What is unique about this object and why
| isn't there a better understanding of its origins given how
| advanced our understanding of black holes and life cycle of
| celestial objects like stars
| pixl97 wrote:
| I think of it as the difference between understanding a lot
| about water and knowing it's made of hydrogen and oxygen versus
| building a microscope that can actually see the molecules and
| atoms interact. You can predict a lot of the behaviors via
| understanding the macro effects of these objects, but when you
| can finally the (scale considered) micro effects you may
| observe some deviations from your theoretical expectations.
| stevespang wrote:
| [dead]
| mountainriver wrote:
| I'm going to say what everyone is too scared to: Starship
| dotnet00 wrote:
| Didn't realize Raptors were capable of FTL!
| baxtr wrote:
| "X7 has a mass of about 50 Earth"
|
| Probably not...
| legrande wrote:
| Or just an advanced civilization harvesting exotic matter to
| power their spacecraft.
| Moral_ wrote:
| Is it a balloon? /s
|
| "One possibility is that X7's gas and dust were ejected at the
| moment when two stars merged," Ciurlo said. "In this process, the
| merged star is hidden inside a shell of dust and gas, which might
| fit the description of the G objects. And the ejected gas perhaps
| produced X7-like objects."
|
| This is pretty interesting, so much ejection due to a merger that
| the light is no longer visible.
|
| Space stories like this always melt my mind because this has all
| happened already , but we're observing it now.
| koheripbal wrote:
| > this has all happened already , but we're observing it now.
|
| In a real sense, it only happens when the light from it reaches
| you. Reality propagates at the speed of light.
| pixl97 wrote:
| Causality is fun. The order in which things happen can be
| different for different observers. With light on earth humans
| don't generally experience this because of the small
| distances involved. But you can design an experiment with
| sound where 3 observers are placed in a large field and 3
| loud noises are made, and each observer will tell you the
| noises occurred in a different order.
| prettyStandard wrote:
| I think about this often. Is this reality's "update loop"[0]?
|
| [0] https://gameprogrammingpatterns.com/game-loop.html
| Eupraxias wrote:
| My head tilted at the title. I suppose "Mysterious object WAS
| dragged into the black hole a super long time ago..." doesn't
| have as much sizzle.
| eternalban wrote:
| https://www.quantamagazine.org/quantum-tunnel-shows-
| particle...
|
| I'm having difficulty parsing your "in a real sense". Are you
| refering to Relativity here or something deeper like
| 'subjective reality'?
| ben174 wrote:
| I can't make any sense of this. It has happened over there -
| so it's happened. How does it make a difference where I am
| standing. I'm not talking about _my_ reality. I 'm talking
| about reality. Things which have taken place and nothing can
| change that.
| adharmad wrote:
| But how do you know that it has taken place without the
| light reaching you?
|
| Without the light (or radiation), all you can say is that
| "something may have taken place everywhere".
| aceazzameen wrote:
| I like to think that the light that reached me is just a
| record of things that already happened.
| adharmad wrote:
| Yes but you cannot tell exactly what happened without the
| light reaching you. Sure you can guess. For example, if
| you know the state of a star a few billion years ago,
| with no other information after that, you can calculate
| at what point it would become a supernova. But without
| the light reaching you, there is no way to tell whether
| it actually became a supernova or something else happened
| (eg - it got swallowed by a black hole etc.)
| kortilla wrote:
| "I can't see it" != "it hasn't happened"
| ianai wrote:
| It might actually be useful to think of that as an
| equivalency because "c" is the fastest rate by which one
| part of the universe interacts with another part. I think
| of the universe branching off by the further in spacetime
| these interactions have to travel. The whackiest QM
| interactions are still bounded by "c." The distances
| between events are called space-like precisely because
| light/etc would have to travel faster than light to go
| from A to B.
|
| Then there's ER=EPR to try to conceptualize.
| adharmad wrote:
| "I can't see it" == "I don't know whether it happened or
| not"
| tyre wrote:
| The person(s) you're talking too are not talking about
| epistemology. If something happened yesterday and I am
| not aware of it until I read the paper today, the thing
| still happened yesterday. If I _never_ read about it, the
| thing still happened yesterday.
|
| Whether/when I "know" about it is separate, and not what
| they're talking about.
| mistermann wrote:
| "I don't know" very often (uncertain topics, for certain
| people) cannot be implemented, that's "just" how it "is".
| aceazzameen wrote:
| I agree you can't tell what happened after a observing a
| recorded event. If you were to read someone's diary from
| a decade ago, you wouldn't know what they were doing now.
| You need new observations.
|
| The OP was referring to when a event happened though.
| heavenlyblue wrote:
| It's like saying that when you see a dead body with a
| sawed-off head nobody knows whether that body was born
| this way or somebody is a psycho who decapitated it.
|
| For the sake if the argument let's allow this body to be
| an light-hour away from us when it happened.
|
| I think your logic is very weak here.
| adharmad wrote:
| What I said in no way prevents us from guessing or
| inferring what could have happened using knowledge known
| to us. But they are all possibilities, some more likely
| than others - there is no way of knowing 100% which one
| of them actually happened without evidence or information
| in the form of light or radiation.
| worewood wrote:
| There is no reality because there is no central authority
| to dictate what has happened and when/where. Your reality
| IS the reality.
| mistermann wrote:
| "The"?
|
| "Is"?
| andrewflnr wrote:
| That's because it actually doesn't make sense. They're
| confused, not you. Source: college physics.
| the8472 wrote:
| In its reference frame light moves instantaneously.
| raattgift wrote:
| tl;dr Neighbouring points on a null worldline are not
| instantaneous because c is not infinite; distant points
| on the same worldline are even less instantaneous. There
| are many useful ways of capturing the "distant" in
| "distant points".
|
| An element of light traces out a worldline. On any
| worldline we can apply whatever labelling-of-points we
| want since relativity is a coordinate-independent theory.
| We can label the points of a worldline with greek
| letters, hieroglyphs, roman numerals, natural numbers,
| real numbers, whatever we like and in any order we like.
|
| One can build an infinity of calculationally-useless or
| misleading sets of coordinates on these worldlines for
| things heavier/slower than light. But one can also build
| an infinity of calculationally-useful and non-misleading
| coordinates for them, and many of those make use of the
| invariant spacetime interval. The same applies to
| coordinates for massless things / things that move at the
| speed of light, even though the invariant spacetime
| interval for light in free-fall is always 0, even if it
| is in free-fall for billions of years (like light from
| distant quasars, or the cosmic microwave background).
|
| A calculationally-useful ordering applies a monotonically
| increasing order from the start to the end of a worldline
| in a time-orientable manifold (our universe is time
| orientable: smaller and denser in the past, bigger and
| sparser in the future). For timelike worldlines (i.e.,
| anything that is always slower than light), almost always
| the most useful ordering is proper time.
|
| But we cannot calculate proper time on a null (lightlike)
| worldline, so we will want some other monotonically
| increasing ordering function on the worldline, and
| ideally one with which we can solve the geodesic
| equation. Such a family of orderings is not only known,
| but has been textbook material since 1970 (Spivak's
| introduction to differential geometry). It's the affine
| parametrization.
|
| For lightlike observers there is thus a useful and well-
| defined notion of time: the affine (parameter) time. This
| is different from but analogous to the proper time
| available to timelike observers. We can do standard
| vector physics on a photon using affine time, e.g. we can
| calculate its phase at various points along its trip from
| point A to point B. (Indeed, talking about a photon's
| quantum wavefunction, the affine parameter is
| proportional to its phase). We can also take the
| derivative of position with respect to affine time as a
| momentum that accurately captures the gravitational
| redshift or blueshift between two points on the null
| worldline.
| edgyquant wrote:
| Reality is relative
| vasco wrote:
| Everything you see "has happened already"!
| [deleted]
| chmod600 wrote:
| How do things in space end up pulled into each other?
|
| If big object A pulls small object B with gravity, wouldn't B
| just speed up and then miss, ending up in some kind of orbit?
| Like, if you are in space and throw a rock at the Sun, it won't
| hit unless you perfectly counteract the relative speed, right?
| laserlight wrote:
| That's right, as explained in the following minutephysics video
| (3 minutes):
|
| Hitting the Sun is HARD.
| https://www.youtube.com/watch?v=LHvR1fRTW8g
| dotnet00 wrote:
| It'd speed up and miss, but say it passes through a cloud of
| gas which acts as drag and slows it down a little, now it
| misses the body slightly less, keep this going for a few
| thousand years and its lost enough energy relative to the first
| body that it can't keep 'missing' anymore and collides/falls
| in.
|
| They're essentially counteracting that relative speed over time
| by bleeding energy to all sorts of drag (one exotic example
| that comes to mind is with things like neutron stars and black
| holes bleeding out vast amounts of energy in gravitational
| waves - literal waves in space-time we can detect from billions
| of light years away - in the moments before they crash into
| each other).
| lisper wrote:
| You can tell that there must be something wrong with your
| reasoning by observing that meteorites regularly impact earth.
|
| You are correct that it is not easy to make things collide in
| space. But it's (obviously) not impossible. The trajectory
| doesn't have to be perfect, just close enough that the lowest
| point in the orbit is less than the radius of the object being
| orbited. In the case of a supermassive black hole, that's a
| pretty big target. The event horizon of Sgr A* is about 50
| million kilometers in diameter, and that is surrounded by an
| accretion disk that acts kind of like an atmosphere, so
| anything that comes close gets slowed down through friction,
| and then it eventually falls in.
|
| (Also, near black holes, general relativity makes things kinda
| weird.)
|
| > if you are in space and throw a rock at the Sun, it won't hit
| unless you perfectly counteract the relative speed, right?
|
| If you are out in space _in orbit around the sun_ this is true.
| But there are lots of ways to be "out in space" not in orbit
| around the sun. The reason that most of the stuff we see is in
| orbit around the sun is that the stuff that is not in orbit
| around the sun doesn't stick around very long. It either flies
| off into deep space, or it falls into the sun.
| grishka wrote:
| I'm getting a 403 both with and without a VPN.
| hnthrowaway0315 wrote:
| Wish I could see it as close as possible outside of the
| Schwarzschild radius.
| pixl97 wrote:
| Even on a 'quiet' black hole I feel the ergosphere is filled
| with enough high energy particles traveling near the speed of
| light that you would quickly turn from an observer into high
| energy x-rays.
| wincy wrote:
| Interesting concept, how close could we get to Sagittarius A*
| without being melted even if we were in a spaceship that was
| 100 feet sphere thick sphere of lead? I feel like the distance
| would be way further than you'd expect.
| hnthrowaway0315 wrote:
| Yeah I guess it doesn't have to be super close. Then sell
| tickets to zillionaires: a lifetime adventure - date with the
| black hole! Are you ready for the pull?
| Trombone12 wrote:
| I'd wait for Genzel to comment, some of us remember the
| disruption disappointment of G2 which they don't seem to comment
| on in the article:
| https://iopscience.iop.org/article/10.3847/1538-4357/acb344
| 00F_ wrote:
| can someone flag this post for its stupid title? the object is
| not mysterious, they say what it probably is right at the start
| of the article. i see the mods change titles like this all the
| time. i dont think this should be an exception. this is really
| frustrating!
| imglorp wrote:
| Clickbait headline, due to lack of mystery. Comment from an
| astronomer saying they have known for 20 years what this X7 cloud
| is.
|
| https://old.reddit.com/r/science/comments/11bk0u1/a_mysterio...
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