Submitted by stealth941 t3_10f735i in askscience
Just the title really, wouldn't it give us more indepth knowledge of a black hole? Yes at some point the signal will stop responding and it may take decades to get to one but why hasn't it be done or thought about?
E - I'm learning a lot here. Mostly similar reaponse but different thoughts. Thanks
Wonderfully thorough answer.
I decided to check some math, and yeah, our fastest ever spacecraft, rounding up, goes 700,000 kmh. At that speed, it would take 156,000 years to reach the nearest black hole.
I didn't even consider the transmission problem, but yeah, conventional communications are a non-option at a fraction of the distance.
What if we put some flaming decals on the spacecraft? In theory, wouldn't that make it go significantly faster?
Depends how you align them. Conventional wisdom says to add racing stripes first, then line any flaming decals up with them so that all the speed is focused in the same direction.
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Decals wouldn't do anything. Painting it red on the other hand... Waaaagh!!
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This spacecraft is called the Parker Solar Probe, and the reason it's that fast is because of the Sun's gravity. So unfortunately we can build a spacecraft that will go 700.000 km/h wherever we want.
>unfortunately we can build a spacecraft
I believe this is a typo, s/can/cannot .
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I mean, so would artificial wormholes, but we have no idea how to make those either.
Speculative, non-existent technology is not the answer to "why haven't we done this yet". The jury's out on whether or not there's any way to circumvent the speed of light, but if there is, we've no earthly idea how.
Wouldn't the Curvature engine as we currently understand it, the Alcubierre Drive require more energy than the output of the known universe?
How is it slowing down? Is it intentional? I have always been told that in the vacuum of space once something is on a trajectory it will continue indefinitely unless something interrupts it.
The Sun's gravity is always tugging on it.
That makes sense and yet I've never considered it. Thank you for answering!
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Huh. So do you know if it will eventually slow all the way down, stop, and start returning towards the sun? Or will some other gravity source capture it before then?
The voyager spacecraft are well above the Solar escape velocity so they will be traveling on out of here.
Nice. Thanks.
As it moves further away the rate of deceleration decreases. It will never stop even given infinite time.
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The cherry on top is the fact that even with the so-powerful-it's-practically-a-weapon transmitter, the data feed would take another 1600 years to come back to us.
Quick correction here: transmission power falls off per the inverse square law only given an idealized isotropic antenna. Focused beams using, for instance, lasers, do not experience the same losses.
But yeah, it's cuz it's far.
But over long distances, it re-becomes inverse square again. After the waist of a laser beam, it spreads out like an inverse square law again, and when you're dealing with lightyears, most of the spread will be after the waist.
Yep! Turns out you're correct (says Google). Lasers do follow the inverse square law. https://www.quora.com/Is-the-light-from-lasers-reduced-by-the-inverse-square-law-as-distance-grows-similar-to-other-light-sources
How powerful the transmitter will need to be is also a function of the gain of the antenna. In this case, the spread angle of the laser
But the spread angle is inversely proportionate to the aperture.
If you send multiple probes that spread out a bit and couple them optically, they can transmit coherently with a huge effective aperture. (like the reverse of a telescope array)
And if the black hole is big enough, you can maybe use its gravitational field to increase the aperture using some mathematical sorcery.
> launched from Earth. It has been traveling for over 45 years and has made it 0.06% of the way to Alpha Proxima
This is not a great example because the point of the probe wasn't to exit the solar system quickly, it was to do science within the solar system. It gets brought up as an example but it really isn't valid because even with the technology of the time we could have sent something out at a higher velocity, but it would have defeated the purpose.
The point was to get to outer planets within a reasonable amount of time, carrying a useful amount of science intruments. Also it has gained speed through gravitational assist.
The New Horizons probe is much more recent, and designed to get to Pluto within a reasonable amount of time. It still took 9 years, and it's actually traveling slower than Voyager now because it's had fewer encounters with planets, and therefore benefitted less from gravitational assist.
Right now, with the current engineering capabilities of humanity, we could get a probe to relativistic speeds fairly easily (in the sense of how many fundamental engineering problems would we need to solve).
If economics aren't a factor, i.e. humanity decides that its collective goal is to make a probe go brrrr as fast as possible towards a black hole, and everyone is working towards that goal (money is no object) then it's actually not that hard. We can send a probe up with a small mass and a huge surface area light-sail, then build high-power laser arrays all over the earth en-masse to point at it.
I haven't done the math, but you could get something up to at least 10% the speed of light this way, probably even 50%.
The bigger problem is a) if we want to send something that has enough mass to actually contain the necessary functionality to transmit back to us from that far, then it becomes much harder to achieve any relativistic speed, and b) it will probably destroy itself after colliding with a dust particle.
And of course thats on top of the fact we'd need to figure out how to power it, we wouldn't see results for 4500 years minimum, and the second it hits that event horizon its gone from our reality forever anyway.
>Alpha Proxima
You mean Alpha Centauri, the triple star system made of up of Alpha Centauri A (aka Rigil Kentaurus ), B (aka Toliman), and C (aka Proxima Centauri). There is no "Alpha Proxima"
Yeah. I combined "Alpha Centauri" and "Proxima Centauri" in my mind somehow.
Is it officially a 3 star system? I read something (probably from this sub) that said it was unknown if proxima was gravity bound to the other 2.
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If humanity really put their mind to it, went all out and built an Orion type spacecraft, we could probably get it there within 3000 years or so.
It's very helpful that the intended destination is to plunge into a black hole, this means we don't need to flip and slow down halfway, so we put more fuel mass fraction into the initial acceleration and we can just smack into it at relativistic velocities.
Transmitting back could be done by a much smaller relay satellite shot backwards some distance from the target, unfurling a massive mylar solar sail with a clever 'shutter' system, using the black hole's accretion disk or a close star as the light source, like a morse light on a ship.. We will work it out.. Of course nothing passes the event horizon but we might get some neat close up images and data for a short while.
> If humanity really put their mind to it, went all out and built an Orion type spacecraft, we could probably get it there within 3000 years or so.
What are the chances that this spacecraft could travel at relativistic speed through space for 3000 years without encountering a speck of dust and detonating with the energy of a hydrogen bomb?
An Orion-class vehicle can carry with it lots of mass to protect it from relativistic dust collisions.
I wonder what would happen if you sent an entangled particle into the event horizon.
Could be an experiment in several thousand years
Nothing would happen.
You can read up on what Quantum Entanglement actually means in this thread.
Sadly, PopSci has completely misrepresented Quantum Entanglement, and it doesn't mean what most articles about the topic says it means.
So the entanglement would break because of how time passes differently close to a black hole?
The problem is that there is no way to communicate with entangled particles alone. Even if we assume perfect entanglement preserved all the way into the black hole, there's no way to send information: this is known as the no-communication theorem.
Wouldn't that be true of any mass? All mass has gravity thus would affect space-time?
Is it really determined how entanglement interacts with black holes? I’d thought that was kinda open. Like, according to the “no hair” theorem they ought to destroy information, but that’s not unitary, which is kinda essential to the behavior of anything entangled with them (and quantum physics in general).
There are proposed resolutions to this apparent paradox but is there a consensus on the right one? And if not, would an experiment near a black hole be useful to distinguish between theories?
Sorry, I shouldn't have implied there was no interesting science to be done with entangled particles and black holes, I meant to just say there is no way of using entangled particles to get information out of the event horizon of a black hole
Wait is the hologram a thing or isn't it?
The holographic principle is a thing. There are hypothetical descriptions of a black hole that say all of the information about the particles that entered the event horizon is spread out on a 2-D layer around the event horizon.
This math could be extrapolated to show that all of our reality is a projection onto the surface of a higher dimensional universe.
There is no proof for this. It is only a mathematical description of one of the ways our universe might look from some higher dimensional perspective. As far as I'm aware, it is based on sound science, but that doesn't mean it is true.
PBS Spacetime on YouTube did a whole series of videos on this.
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Somewhat off topic, but why isn't it possible to get information out by setting up a bunch of orbiting relay satellites? Photons can travel from hop to hop since the distance between them is arbitrarily short so my intuition tells me that you should be able to relay information out even if you can't transmit directly. What is it that I'm missing?
Outside the event horizon, sure.
Inside the event horizon, space is warped in such a way that the only paths going towards the event horizon are in the past. Going forward in time, all possible paths go closer to the singularity.
How do black holes evaporate through Hawking Radiation if nothing can escape?
Hawking radiation just appears (poof), it doesn't actually cross the event horizon.
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Hawking Radiation is theoretically not at all related to the contents of the black hole; it should be random.
However... that means that when a black hole evaporates completely, all information that entered it is destroyed. This is a huge open problem in quantum physics known as the Black Hole Information Paradox.
Interestingly, one recently discovered possible solution is that information is able to exit the black hole via wormholes that could mathematically exist, but don't... https://www.youtube.com/watch?v=epSev7ovVew
But really, we just don't know yet for sure. It's certainly possible that Hawking's original description of Hawking Radiation is incomplete or subtly wrong.
Whether it's photons, radio waves, neutrinos, or relay satellites, you're still trying to gain information from an area that nothing, not even signals, can escape once it's inside.
Edit to say ignore the neutrino part. I'll save an edit to say I know antineutrino has to be said.
You could, yes. The trick would be getting relay satellites to those intermediate points and keeping them there.
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Wow, everything you stated was news to me. Thanks!
So does that mean all the SETI stuff is basically pointless? Is there even vaguely conceptualized broadcasting technology that could be built consistent with the laws of physics that could hypothetically reach us from another solar system?
We could communicate with an alien civilization with Earth-equivalent technology over something like 100 light years. It's more difficult than communication with Mars - you need more power, larger antennas and you'll get a lower bandwidth - but it's possible. If the aliens have more advanced technology then the distance could be much larger.
Is that 18 quadrillion number wrong then? Or what am I missing about that? Because that order or magnitude doesn’t even sound like a real number. If I’m counting zeros right, that’s 18 thousand million million times more power than doing it from Mars?
It's assuming identical conditions otherwise.
Combined that's a factor 150 trillion, so we are only worse by a factor 100 or so. We won't get the multi-megabit connections we can get from Mars, but it's still good enough to transfer tons of information over time. There is no rush - it will take 100 years to arrive anyway.
Thanks for that!
The 18 quadrillion is to get out to 1600 light years, as opposed to 100 light years as /u/mfb- is talking about.
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But even if we had the speed, would anything survive passing through the kupiter belt or oort cloud? Or are they less dense with debri than I imagine?
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Thank you.. I know nothing about anything but understood most of what you said.
Impulse Radiating Antennas have managed to get around the inverse square law. They've been in study for the last 40 years.
http://www.farr-research.com/ has tons of info on them.
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I'm sure that if the solar system contained a black hole, it'd be a major priority to get a space probe out there to study it firsthand.
But it doesn't; the nearest black holes are hundreds or thousands of light years away, meaning a probe would need to travel at the speed of light (far faster than anything we could build) for hundreds or thousands of years to reach it, and the signal would take just as much time to be sent back. We simply do not have the technology to visit other star systems and other astronomical objects beyond the solar system.
Even if we did, the same physics that make it impossible to detect information about the inside of a black hole with telescopes from the outside, also makes it impossible to receive data from within the event horizon. We'd basically be studying the same phenomena we see around black holes already--gravitational lensing, accretion disks, relativistic jets--but from up close instead of through telescopes.
Mainly the distance to the next black hole.
The closest Black hole is 1.566 Lightyears away from us. That's 99035 AUs
The furthest object we were able to send into space is Voyager-1, which got to 159AU in 45 years.
So, the closest black hole is 622x further away and would have taken Voyager-1 about 28,000 years to get there.
Which means, if we send a probe now, it will arrive at the black hole around the year 30,000
The nearest black hole to us isn't 1.6 lightyears away, it's 1600 lightyears away.
sorry, my mistake. (US and Europe use "." and "," in different ways")
So it's 622,000x as far away and would take 28m years. (or 1000x as long)
Same argument though. Anything exceeding the life-time of a few generations on earth is currently unfeasible.
FYI the difference in "." and "," isn't a Europe/US difference. The UK also uses the decimal point "." as do most English speaking countries along with former British colonies such as India and Pakistan. Additionally Most of East Asia also uses the decimal point, including China, Japan, the Philippines, Thailand, and Malaysia. Indonesia and Vietnam are the exceptions in that region. Most of Central America and the Caribbean does too, with Cuba and the Dominican Republic being exceptions (plus a few of the smaller islands and overseas territories of European countries).
Additionally, due largely to English's influence on their development, most major computer languages use the decimal point (and don't use thousand's separators at all). Some computers and programs CAN handle input as text that uses the decimal comma, but its not universal.
Long story short though, in English you're better off using the decimal point to avoid confusion.
I can handle both, but when switching between sources it's easy to mix things up.
Every programmer had to suffer through that inconsistency in numbers.
I'm willing to take that chance for future generations... I mean its comforting knowing that's where the closest black hole is
E- yh I was naive there I'm learning as I read
I mean, i get what your saying, but this requires funding. And like other commenters have said, it wouldn't be able to transmit anything back to us, not only that, I don't think the information gained would even seem that useful, to justify an operation that would be 60,000 years into the future, when it's unclear if we'll be around for another 100 or so
Unfortunately movies like Interstellar (which I love btw) make it seem like simply entering a black hole would reveal all sorts of secrets of the universe to an observer. All we really know is that most of our physical models break down in there, and without a massive lineup of experiments and machines to conduct them to take into the black hole, let alone the current impossibility of doing so, it would be akin to you doing 5 tabs of acid and then telling the rest of us 'you've figured it all out'.
The latter would be a lot more enjoyable.
It's not a matter of "taking chances." We don't have the technology to send a probe to even the closest stars (other than our Sun). And the closest black hole is hundreds of times further away than the closest stars.
I have been made aware that my calculation was off by a factor of 1000.
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>I'm willing to take that chance for future generations
All of recorded human history would not cover 1/10 of the time this journey would take. Being optimistic, I would hope that whatever we send today would be considered beyond an ancient, obsolete relic before it arrived at a black hole.
Additionally, the speed of this probe is actually the easiest problem. Then it has to be constructed to endure the massive gravity that will tear it apart on a molecular level. Then, we have to figure out how to transmit any data back from something that doesn't let light escape.
Yh sounds insanely complex
Another thing to consider is that a probe sent by future generations would almost certainly beat a probe sent today to the destination due to advances in propulsion technology.
If we could, the probe will never enter the black hole's event horizon from our perspective...
It will slow down to come to a halt just before the event horizon.
From the probe's point of view it will enter without any problem if the hole is big enough. (otherwise it will turn into spaghetti)
It will eventually enter the event horizon even from an outside perspective. If it didn't literally EVERY object ever would appear to be hovering just outside the event horizon. The reason this doesn't occur is because the event horizon isn't a fixed point, it expands as things fall in.
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It wouldn't be any use. No information can traverse the event horizon: your probe might be inside there, looking around. Hell, it might even make it through to the other side of the black hole! But you wouldn't know it because no light can escape and tell us what's going on.
Of course, the more difficult problem is that there are no black holes (that we know of) inside the solar system. At present, only two probes have made it beyond the bounds of our own solar system, and only by a short hop. The nearest black hole is a lot farther than that.
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Hey just think about how long it will take to get there 1,600 light-years away......Then add on how long it will take for the information to get back to us.
One way is long enough but you still need the return trip on the data collected to travel back. That is a long...long, long, long time. I mean...I don't even know how you send that data back from that distance and escape the event horizon anyway.
Edit: Crap I should have read the responses...someone already made much more detailed post saying the same things. Well done /u/Weed_O_Whirler
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The nearest "black hole" is probably tens of thousands of light years away from the Earth. No one is sending a probe, unless you wish to wait for a very very very long time to get there and a very very very long time for any results to be returned.
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First, we need to deal with the fact that there isn't a blackhole anywhere close. The closest is probably several thousand light years away. Basically, any blackhole is considerably beyond our reach. This is all before we can consider designing a probe that could somehow survive the trip there and then the immense gravity of the blackhole. Lastly, any information we could possibly gather would itself be trapped by the gravity of the blackhole.
TLDR: The distances are too great, nearly impossible to send the probe beyond the event horizon, and the information itself would be trapped with no escape.
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How about the distance (and time to reach) to the nearest black hole? Plus the fact the information from the probe cannot escape the event horizon of a black hole, and the stresses of entering a black hole will rip it apart. Just a few reasons to start.
As the probe would approach black hole the time around it will slow down and it would take thousands of thousands of years for the probe to fall in, from the probe perspective it would take a couple of minutes of course. Also after it crosses event horizon we can no longer get information what’s going on as even weightless radio waves are getting pulled in
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“Space is big. Really big. You just won't believe how vastly hugely mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space.” - The Hitchiker’s Guide to the Universe, Douglas Adams
The nearest black hole is 960 light years (5.63e15 miles) away. The fastest spacecraft is the Parker Solar Probe at 430,000 mph. At that speed, it would take 1.22 million years to get the probe there. There’s both technical an economic issues in preparing for a 1.22 million year mission.
> The fastest spacecraft is the Parker Solar Probe at 430,000 mph
This is simply wrong. The value you provided is instantaneous velocity this spacecraft had when passing perihelion, and is mostly due to how close to the Sun it was. It has very little to do with actual velocity at which it would travel outside the solar system.
Highly elliptical or hyperbolic orbits look a bit like pendulum or a ball thrown upwards -> you have high velocity when it's deep in gravity well (eg. ball is the fastest right before hitting the ground) but the velocity drops when you're moving away (eg. the ball will essentially reach a point where it has velocity=0 before it starts falling back down). So while parker solar probe had high velocity when passing close to the Sun, it would be moving orders of magnitude slower when moving away, eg. in the direction of this nearby black hole.
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Information, like light, propagates at the speed of causality. The gravity of a black hole is enough to prevent anything from leaving the surface, even if an object could be engineered to survive, deployed, and reached within a human lifespan.
The vast majority of black holes have accretion discs, which have such high amounts of hard radiation, any probe would be fried long before it gets anywhere remotely near the black hole.
Besides hard radiation, the only other really cool things we'd want to investigate are either gravitational (we don't have super-tiny gravity sensors to my non-expert knowledge) or quantum in nature (and I don't think we have a particle accelerator we can fit into a space probe.
And, using current spaceflight tech, it would take thousands of years to get a probe anywhere near one. So it would be an expensive investment, which might give us useful data in thousands of years.
>The vast majority of black holes have accretion discs, which have such high amounts of hard radiation, any probe would be fried long before it gets anywhere remotely near the black hole.
That's not true. Otherwise they should've been much easier to locate.
>And, using current spaceflight tech, it would take thousands of years to get a probe anywhere near one. So it would be an expensive investment, which might give us useful data in thousands of years.
*Hundreds of thousands
>Besides hard radiation, the only other really cool things we'd want to investigate are either gravitational (we don't have super-tiny gravity sensors to my non-expert knowledge) or quantum in nature (and I don't think we have a particle accelerator we can fit into a space probe.
Aside from the broken English,what¿?
Weed_O_Whirler t1_j4w0gjz wrote
> it may take decades to get to one
This is the main problem. It wouldn't take decades to get to one, it would take hundreds of thousands of years.
Voyager is the furthest probe ever launched from Earth. It has been traveling for over 45 years and has made it 0.06% of the way to Alpha Proxima, the closest star to Earth- and it's still slowing down. The closest known blackhole to Earth is 400 times further away from Earth than Alpha Proxima..
Of course, even if we got a probe there, it would have to have more power than any transmitter ever made to communicate with us. Transmission power falls off using an inverse square law meaning you would need ~18 quadrillion times more power to communicate back to Earth from that blackhole than it would take to communicate back from Mars.
And to top it all off, even if we somehow conquered all of that- once the probe actually entered the blackhole (aka- crossed the event horizon) it is physically impossible for it to send us information anyway, since nothing can escape a blackhole's even horizon.