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I never got the grasp of my "Misner, Thorne and Wheeler: Gravitation", but I seriously hope that the astronomers find enough black matter to ensure that universe will eventually collapse into a huge Gnab Gib, the ending time.
I never was comfortable with eternity, never could accept it as a physical reality. I am happy with Big Bang, the start. I would like to know that it is ending as well. Not only "us", but time itself.
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trønderen wrote: I seriously hope that the astronomers find enough black matter to ensure that universe will eventually collapse
Without going into any details, it looks to me that the matter that falls into the singularity at the center of our galaxy shares space with the matter outside. I could be wrong, but that's the conclusion I arrive at when I explore with geometry. I'm probably wrong.
trønderen wrote: I never was comfortable with eternity, never could accept it as a physical reality. I am happy with Big Bang, the start. I would like to know that it is ending as well. Not only "us", but time itself.
I don't have any answer for this, no idea.
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Well, the Hubble telescope caught a small planet being drawn into a black hole last year. In fact, the detail of the image was so good that you could see the lawyers rushing to the scene.
anonymous.
>64
If you can keep your head while those about you are losing theirs, perhaps you don't understand the situation.
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What they just saw the planet get very close.... You never seen one cross the event horizon. Not just because light can come back from the event horizon, but also because as you get increasingly close to the surface, time freeze....
look some detailed information here if you insist
Does time pass faster or slower close to the black hole?
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The sun revolves around Sagittarius A*(the name of the Milky Way's black hole) just like we revolve around the sun. But don't worry about the black hole. The sun will expand and swallow us all well before we have to worry about a black hole. Not to mention in a few million years we will get to meet our neighbors in the Andromeda Galaxy, when our galaxies collide and combine! 
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Super Lloyd wrote: Which mean, good news, next time you fall into a black hole, you will only cross the event horizon by the end of times....And it will only take you 5 minute - of your own relative time, so you don't even have to wait!
Wasn't mentioned but those thought experiments involve particles. Not people.
You would be dead long before you could see any relativistic effects. If not radiation then differential gravity would tear you into pieces (particles.)
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jschell wrote: If not radiation then differential gravity would tear you into pieces (particles.)
Haha.. this effect that you mention, also known as spaghettification, only happen for "small" black hole. But doesn't happen with the really big one at the center of galaxies. Their event horizon being way too large, the gravity gradient is not significant at the event horizon.
Granted I didn't specify I was talking about those, but thing is, it just doesn't happen all for all blackholes! 
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I've mentioned here before that whenever I catch myself forgetting that I don't know it all, I try my hand at a brain teaser I've been trying to solve for years now.
The problem is simple: Convert a finite automata to a regular expression.
The solution had eluded me. I've attacked it many different ways.
Finally I settled on the state removal method as it generates the cleanest regular expressions, and seemed easier for me to understand than methods like Arden's theorem: R=QP* whatever the heck that means.
Anyway, I solved it I think. I still need to create a battery of tests, but it seems to be working so far.
(abcd|12(3|55|77|99)4)(ef)*g
q0:
(12(34|554|774|994)(ef)*g|abcd(ef)*g) -> q1
*q1:
(12(34|554|774|994)(ef)*g|abcd(ef)*g)
It's not the exact same regex, because that's not necessary. It just has to match the same text as the original one matched.
If anyone is curious, here's my mess. The main meat is in Program.cs under the ToRegex() method in the main project. The rest is support.
GitHub - codewitch-honey-crisis/FAToRegex: A testbed for FA to Regex via state removal in C# (work in progress)[^]
Anyway, point is, now I need another problem I can't solve, that students can, that I can attack for years to keep me humble.
Real programmers use butterflies
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honey the codewitch wrote: I need another problem I can't solve
Looks like you are using the state elimination method, so I would argue that you haven't fully solved the problem until you can do it with Arden’s method.
Or maybe you can do the reverse and convert a regular expression to a DFA next.
Best Wishes,
-David Delaune
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I already do convert regex to DFA.
I could use Arden's theorem, but I wouldn't feel humbled by it. Learning it requires a pretty solid grasp of mathematical formalisms and symbols that I still struggle with. Learning that stuff will take awhile, and not knowing it doesn't really bother me. I've never strictly needed it, although at times it would be helpful, admittedly.
But my point is because I don't know those things, not being able to solve it using Arden's theorem isn't something I feel like I *should* be able to do. Sure, I have instructions, but they are quite literally Greek to me. 
And Arden's theorem produces an inferior result to the state removal method, so there's no practical reason for me to solve it that way.
I may do it one day, once I have those formalisms under my belt much better than I do now, but for now it wouldn't scratch the same itch for me. I have a feeling when I do master those formalisms, Arden's theorem will be easy to implement. It's obviously recursive. I can "see" some of it, but through a glass darkly. I've even got an inkling of an idea of how it works. So I can see that it's easy to do if you understand those formalisms - likely *easier* than the state removal method.
Edit: I'll get some additional challenge out of refining it, but nothing that will replace what not being able to solve the problem did for me. Oh well. On to new challenges. I'll find something. Maybe it's time to dive into the back end of compilers instead of the front end. I've written an assembler and disassembler for a pike virtual machine in C#, so maybe I should write a compiler in C# just so that it can be tinkered with. Maybe therein I'll find a problem among the weeds that will satisfy me the way this one did.
Real programmers use butterflies
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So my audio playback on the laptop was breaking up constantly. So I tried my other laptop, and same thing!
Both are running W10, so I figured a Microsoft broke something in an update. So down the rabbit hole I go:
1. Rebooting didn't fix anything.
2. Drivers were all up to date.
3. Different audio playback proggies all exhibited the same problem!
4. Even Audicity!
As Holmes would say, "Quote: Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.
I decided to look at the main speaker interface -- it's one of those cheap Logitech speaker systems that has a bass-y speaker in the main box and little speakers for the stereo stuff and the bass is so gawdawful that I snipped the wire, I still have to add it the audio pot that I bought to control the volume, but I digress...
And what do I find?
The power plug input to the box is not fully seated in the receptacle!
Push it in properly, and no more breaking up of the audio! I guess certain frequencies of the audio (not very high, mind you) was somehow reverberating into the box just enough to momentarily break the power connection.
Sorry to blame you, Microsoft and W10! 
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Marc Clifton wrote: Sorry to blame you, Microsoft and W10!
You shouldn't be, Marc. As any good engineer, you first traced the most likely path of failure. 
/ravi
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Remove any "Antivirus" suite that was shipped with it. It's likely Mcafee Livesafe. Windows defender will supplant it and it is sufficient for most heathens. 
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Marc Clifton wrote: Sorry to blame you, Microsoft and W10!
That should be for all the things they did you didn't catch, undocumented features? 
The less you need, the more you have.
Even a blind squirrel gets a nut...occasionally.
JaxCoder.com
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My wife's laptop has a dodgy power connector (in the laptop, not the cable). Yesterday she came to use the laptop and it was dead, despite being on charge overnight. She spent 15 minutes wiggling the connector in the laptop power socket, trying to get some power into it. Eventually I offered to have a go, but before doing that I looked at the mains socket. Which was off.
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I just got to understand display port is not HDMI. before I took display port for granted as HDMI interface.
today I try to hook my monitor with my DELL T5810 by HDMI cable. but it turns out the interface on the DELL chassis is a display port interface, not HDMI.
so I have to buy another adapter (display port to DVI)to connect it to my monitor.
also I find this link is useful.
diligent hands rule....
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Southmountain wrote: I have to buy another adapter
And they are not cheap, I found the same problem, 2 display ports do not fit my old HDMI monitor. I will eventually get an HP monitor just to see if there is a difference in resolution.
Never underestimate the power of human stupidity -
RAH
I'm old. I know stuff - JSOP
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now I can recognize four interfaces: DVI, VGA,HDMI, and display port plus choice of female or male type.
diligent hands rule....
modified 25-Dec-21 22:22pm.
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Is this a useful invention It is intended to aid the unsighted Imagine a 2D array of small audio output devices let's say 100x100 Assume they are small enough to allow such an array to span the width of the face or perhaps even full around the head Further assume a video system permitting 3D information Now convert the visual 3D to audio 3D onto the array I await your more knowledgeable reply - Cheerio
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Probably more useful: a diaphragm-device you can place over each ear that reproduces audio signals via electrical voltages. So a production can have an actor say, "The stage is lit by 1000 Christmas tree lights of every color" and the person without sight can vainly try to picture color from that auditory input, instead of vainly trying to picture colors based off the simultaneous input of thousands of speakers emitting sounds around the entire periphery of the head.
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May I please request consider the production actor speaking over the diaphragm device placed over each ear powered by electrical voltages may not be able to inform the unsighted as to how to prepare dinner Re/ diaphragm devices I favor the Spendor A7 but lust after the D9.2 - Cheerio
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Something to navigate by would seem more desirable (first); where you wouldn't necessarily have to have 2 good ears. Sound / noise / pressure wave forms. Tie in the space-mapping found in AR (headsets).
"Before entering on an understanding, I have meditated for a long time, and have foreseen what might happen. It is not genius which reveals to me suddenly, secretly, what I have to say or to do in a circumstance unexpected by other people; it is reflection, it is meditation." - Napoleon I
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You are quite correct Our unsighted friend is assumed to have two good ears May I please inquire does AR not require two good eyes - Cheerio
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No ... it requires good cameras, for starters.
"Before entering on an understanding, I have meditated for a long time, and have foreseen what might happen. It is not genius which reveals to me suddenly, secretly, what I have to say or to do in a circumstance unexpected by other people; it is reflection, it is meditation." - Napoleon I
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Happy Holidays My question was in regards so called "spatial mapping" to which you referred I looked the term up on internet to learn it involves visual presentation of 3D information obtained from infrared cameras as per "HoloLens" The critical term here is "visual" which of course is of no use to our unsighted friend - Cheerio
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