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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.

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SaltyDangerHands t1_j4w365s wrote

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.

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champybaby t1_j50amrp wrote

What if we put some flaming decals on the spacecraft? In theory, wouldn't that make it go significantly faster?

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SaltyDangerHands t1_j50m9ky wrote

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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turnturnburn t1_j52c7vd wrote

Decals wouldn't do anything. Painting it red on the other hand... Waaaagh!!

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_HelloMeow t1_j4zcwr3 wrote

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.

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Abu_mohd t1_j4zyk9a wrote

>unfortunately we can build a spacecraft

I believe this is a typo, s/can/cannot .

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[deleted] t1_j4yt713 wrote

[removed]

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SaltyDangerHands t1_j4z1dgh wrote

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?

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Karontu t1_j4wnbf8 wrote

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.

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Weed_O_Whirler t1_j4wo3n3 wrote

The Sun's gravity is always tugging on it.

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Karontu t1_j4wpb4p wrote

That makes sense and yet I've never considered it. Thank you for answering!

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-YellsAtClouds- t1_j511sis wrote

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?

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starmartyr t1_j5cj65o wrote

As it moves further away the rate of deceleration decreases. It will never stop even given infinite time.

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malastare- t1_j4xr9k8 wrote

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.

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Fair-Ad3639 t1_j4xdvau wrote

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.

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Weed_O_Whirler t1_j4xgk6q wrote

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.

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Fair-Ad3639 t1_j4xitxi wrote

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

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dumb_password_loser t1_j4zja46 wrote

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.

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chcampb t1_j4w7u93 wrote

> 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.

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aspheric_cow t1_j4wylqe wrote

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.

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Lucifernal t1_j5df2xc wrote

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.

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urzu_seven t1_j4za0xs wrote

>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"

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Weed_O_Whirler t1_j50sb85 wrote

Yeah. I combined "Alpha Centauri" and "Proxima Centauri" in my mind somehow.

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ElderWandOwner t1_j525cut wrote

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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ozspook t1_j4zdloy wrote

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.

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jrob323 t1_j4zjml5 wrote

> 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?

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Wyg6q17Dd5sNq59h t1_j4zyd33 wrote

An Orion-class vehicle can carry with it lots of mass to protect it from relativistic dust collisions.

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AussieWalk t1_j4w9eth wrote

I wonder what would happen if you sent an entangled particle into the event horizon.

Could be an experiment in several thousand years

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Weed_O_Whirler t1_j4wau8u wrote

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.

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[deleted] t1_j4yj5wc wrote

So the entanglement would break because of how time passes differently close to a black hole?

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purpleoctopuppy t1_j4yq9a6 wrote

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.

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_Tonan_ t1_j4yn7r3 wrote

Wouldn't that be true of any mass? All mass has gravity thus would affect space-time?

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bitwiseshiftleft t1_j4y46mc wrote

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?

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Weed_O_Whirler t1_j50t0e7 wrote

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

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blscratch t1_j4yqb0h wrote

Wait is the hologram a thing or isn't it?

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midnight_mechanic t1_j57qch7 wrote

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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NeuralParity t1_j4wfm4i wrote

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?

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Lyrle t1_j4y1c61 wrote

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.

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beipphine t1_j4y5bdw wrote

How do black holes evaporate through Hawking Radiation if nothing can escape?

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Lyrle t1_j4y5nvp wrote

Hawking radiation just appears (poof), it doesn't actually cross the event horizon.

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kilo-kos t1_j56towp wrote

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.

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blscratch t1_j4yotxl wrote

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.

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NDaveT t1_j4wg45g wrote

You could, yes. The trick would be getting relay satellites to those intermediate points and keeping them there.

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moralprolapse t1_j4yu3i0 wrote

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?

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mfb- t1_j4yvrjf wrote

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.

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moralprolapse t1_j4ywwen wrote

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?

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mfb- t1_j4yyr6f wrote

It's assuming identical conditions otherwise.

  • Replace the ~1 meter antenna of a Mars spacecraft with a 500 meter telescope for a gain of 250,000.
  • Increase the power from ~100 W to ~5 MW for a factor 50,000.
  • Replace the 70 meter antenna of the Deep Space Network with another 500 meter antenna for another gain of 50.
  • Replace the 1600 light years used for the 18 quadrillion number by 100 light years for another gain of 250.

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.

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Weed_O_Whirler t1_j50tbgd wrote

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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dirtylostboy t1_j50zvi9 wrote

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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aversionals t1_j5b98aa wrote

Thank you.. I know nothing about anything but understood most of what you said.

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