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Messages - Agent : Orange

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Alpha Centauri, our nearest star system, is 4.37 light years away. Getting there with current technology would take 78,000 years. Breakthrough Starshot wants to get there in a lifetime.  A team of scientists and entrepreneurs, led by Russian philanthropist Yuri Milner, have announced an audacious plan to send thousands of smartphone-sized craft into orbit around the Earth and onto the stars. ... Once in orbit around Earth, the swarm of craft would unfurl lightweight, thin sails which would then be hit by high-powered lasers based on Earth, propelling them at one-fifth the speed of light.  At such speeds, the craft would reach Pluto in three days, a feat which took Nasa's New Horizons more than nine years. After 20 years Breakthrough Starshot would reach Alpha Centauri.

I love it that I live in a time when this is being discussed seriously.


A short blurb about this view of a gravitational lens system from ALMA can be found here:
The fuzzy white patch is found by modelling. It is a mass of dark stuff that is needed to match the model to data.
Pretty amazing!


I know people who have put a lot of work into this project. I hope the situation is not as serious as it appears to be.

Thanks AO

A repeating FRB is a real surprise!

Some more fast radio burst business.

A new study calls into question whether or not the previous distance estimate is correct at all, as it now appears that the post-burst radio transient behavior may have been due to a nearby AGN acting up in a variable way, and not an associated transient event. So the case is far from closed on the distance to the source of the FRBs and the question of whether they are galactic or extra-galactic seems to remain open for now.

More surprisingly, an FRB has now been seen to repeat, which is unexpected and a real game-changer. It means the source of the burst is not destroyed in the process and can repeat this activity over short timescales. Over 10 aperiodic repeats of the bursting behavior was observed from May to June 2015. Posted today on arxiv and published in Nature.

General Discussion / Re: Video Gaming
« on: February 25, 2016, 07:15:31 AM »
Finished off A Link Between Worlds. Loved the special power, but I wish the maps weren't the same as in the SNES game. It felt like more of a rehash than a completely fresh outing.

Next on to New Super Mario Bros 2. :)


This is really groundbreaking and advances the study of the FRBs. For a long time the astronomical community has been debating if these things are local or cosmological, so having a confirmed host is an exciting development. Now will be the time when we begin to really learn a lot about them. Not surprising it was at Parkes either, many of the FRBs have been discovered there and a few at Arecibo as well. Anyway now we know that they have an origin at cosmological distances the real detective work can begin. Current thinking points toward a relationship to magnetar flares or other outburst, whether or not this holds up will be interesting to see.

Then I can expect your full analysis in the morning?

I think you just got it! :)

At least Duchovny could act when the series began. Agent Miller is like a combination of young Anakin Skywalker crossed with that werewolf from Twilight

No beginning to the Universe?


I met Das once and attended a talk that he gave, and had a bit of time to chat afterward too. His work is very interesting. I'm curious to learn more about his approach. At first glance it seemed to me that the Raychaudhuri equation he makes use of as well as the Bohmian path business is interesting and seems like a rich direction to explore. Whether any observational tests can be found for these ideas would be very exciting.

I'm discouraged by the fact that Carter did not approach this as a six episode arc that was internally consistent. Instead it wandered around - really, aimlessly - in the middle. It's not the biggest boost of confidence going forward.

Einstein and Miller don't have much chemistry and I found neither were very convincing. I've also been watching Lucifer which is after the X-files in my area and which is also bad. But I feel like the psychiatrist in that show should have been cast as Einstein and would have been a much better fit in that role.

I like watching a show regularly and all, but I've gotta call it when I see it. Sorry to say, the overall arc and the finale especially let me down. Vicious and vaguely lovable though it may be to say.

Alright then:



It bothers me that Mulder and Scully's son is involved and I don't like that he will be the messiah. The tension and relationship between Mulder and Scully for me was also a ruined by the amount of history they have behind them now. I like that they advanced the cigarette smoking man but I felt like it was an episode I'd already seen when Mulder holds a gun to his head. Also wasn't CSM supposed to be Mulder's father at one point?

Ultimately minor nitpicks compared with the overall pacing and how uneven these episodes have been for me. If no further movie or season is released that series finale is weak. 

Is it necessary to post a spoiler alert? Or should I just assume everyone here is already familiar/ready to be spoiled?

Goddamn! Why'd they cram all of THAT into one episode and meanwhile waste an entire show on the were-lizard?

I would have been on board if it was given some time to breathe and develop. But instead it was all shoe-horned into an hour. Sorry to say but this whole thing feels really poorly planned to me.

Posted yesterday. I have not yet had the chance to read it but I include it here because it's directly applicable to a claim made earlier in the thread.
Hawking radiation from black holes as a possible probe for black hole interior structure:
To summarize:
"Hawking radiation is one of the rare methods we can apply to infer some but usually little information from the black hole. Hawking radiation is not yet successful in unfolding the interior structure for traditional black holes. But we conjecture that in the case of regular black holes, the Hawking radiation might be a powerful probe into the black hole interior structure."

So some types of black hole models do seem to leave a fingerprint of their interior on the properties of their Hawking radiation.

Largely disappointed that this wasn't one big 6 part story arch. 

Lost it at Mulder's country line dancing though.

Yeah, that surprised me too. I was expecting maybe a monster-of-the-week or two. I really hope the last episode ties the series together well.

Technology / Re: FUNCTION RANDOM - All Things Technological On Your Mind
« on: February 20, 2016, 01:58:18 PM »
Want to know how your computer works ? Dated info focusing on C and 'nix systems, but still relevant.
Free online Computer Science 101

This is really useful and interesting. Thanks for posting.

Technology / Re: FUNCTION RANDOM - All Things Technological On Your Mind
« on: February 19, 2016, 09:50:23 AM »
Ran across this today.

That cable job is brutal, though!

General Discussion / Re: Video Gaming
« on: February 19, 2016, 08:38:02 AM »
That's it, modded Skyrim looks like the best game I've ever seen

Now perhaps Agent : Orange has the mathematical chops with quantum chromodynamics to answer this question decisively, but it seems plausible to me that there could be some kind of Pauli-exclusion-like principle with quarks that would prevent the matter of the singularity from forming a true point, or two-dimensional ring.

Thanks for your kind words Chronaut. While quark degeneracy can't prevent a black hole, but a lot of people in the field speculate that quark stars may be an intermediate step between neutron star and black hole. There are a lot of interesting ideas out there about the types of supernovae that these would result in and other predictions regarding supernova remnants. There is also a wide gulf between our understanding of all the different kinds of neutron stars that we see out there, particularly in terms of their outburst and flaring activity.

Sad to say chromodynamics is far afield for me, but I do know how to use the results of nuclear many body simulations other people have done to make neutron star models from the equation of state.

General Discussion / Re: Video Gaming
« on: February 18, 2016, 05:55:14 PM »
Zelda has been a complete blast for me.

"We have need of a hero -- and your Dr. Ass is superb."

I don't know if I'm using the right terminology here, but can one of you explain how a large mass can collapse to a single point in terms of a quantum field?   
Well that's the exact problem that quantum gravity grapples with, singularities make problems for the uncertainty relation because they have an exact position. Funny things will happen when you approach them and it's not at all clear what they mean for quantum mechanics. That's why you need quantum gravity. All we can say classically is about the parts we can observe, shadow, etc. And as Chronaut rightly points out, the ringdown which is the key to this question. No one knows if you can put a whole stars mass into the volume of a quark. Unsatisfying. But it's a mystery. That's also the problem with the big bang, too, and why we can get right back on the fringes of t=0, because a similar problem happens there.

As AO expressed early on in this thread, we should really think of everything in terms of fields.   Mass, as far as I understand, is just a fluctuation in this field, when great enough there is quanta that becomes say a proton (or a quark whatever). 
In 2D terms, I think of an oscilloscope, and maybe this is the wrong way to think about it, but let's say you have a particle (a bit of mass) when the scope reads 5 volts at a wave crest.   Is that a fair, albeit overly simplistic analogy?  In that example, would a lot of mass close together be a higher frequency in the field?   
A big red flag of caution goes up here. It's really hard to make these kind of mechanistic analogies, you're getting into the region where it's difficult to really understand what's going on without doing some math. So our discussion with analogies can only really go so far. Quantum mechanics is counter-intuitive and the english that works to describe one case may fail in another.

The best I can say is that the wave that accompanies a particle is a wave of probability, and that you're more likely to detect a particle of mass m at a crest of the wave rather than a trough. Somewhere in that wave we could detect a particle. And, you can also think of the wave properties as depending on the momentum (or energy if you like), the wavelength and particle momentum are inversely related to one another. Anyway that's why it's hard to tell what the position of the particle is.

And, that's what's going to make all the problems for black hole singularities, if that's where you're going. We can't really sew the spacetime curvature and wave-function descriptions together, we really don't know how. GR lets us describe a black hole classically but when you start asking "what's the wave function of a black hole" you're up against a wall because there's no good answers and a lot of speculation. So my answer is: wait and see.

Anyway that discussion of wave and particle properties is the basis for the double slit experiment, and Feynman said that's all you need to understand quantum mechanics. So maybe it's a good place to start for black holes too.

Some guy in the Tenderloin was trying to sell me some crystal last weekend.  I know that some of these physics geniuses are idiosyncratic and don't pay too much attention to their grooming or hygiene, but this guy looked like a drug addict and not a physicist, so I passed.  Had no idea he was offering me a pathway to another universe.  He only talked about it taking me to the moon.

I wonder if he's still trying to sell that thing.  BRB guys, imma check it out.

Make sure you get the blue spacetime crystal.

I reread my statement and yes I agree I was confusing mass with mass density.   I do know the difference, I don't know why exactly I said that.   

How's that?

The details of how a newly formed black hole relaxes after a merger will have a lot to do with the structure of the horizon would presumably be influenced by internal structure if any existed. Which again, it doesn't to the best of our understanding. See also the event horizon telescope,

I've got more to say but I need to go do something so I'll just keep the conversation flowing with this..  I don't dislike GR, I'm simply asking is there any physical evidence that there can't be a body inside the event horizon? 
From what we understand about compressibility and the pressure-density relationship of matter under extreme circumstances we don't know of anything that can stand up to the extreme gravity inside. It should all be very nearly pointlike. Please don't get me wrong, that's by no means the whole story, surely there are quantum effects that are important at the singularity. The current thinking is that these will smooth out the singularity to prevent an infinity there. Many people also have other ideas about what might be in there from string theory also. But again, the horizon and external geometries reduce to GR within the observational error margins, as they must, for all these models.

You say no, but only give a model, which GR is, even though at least from all past experiments it has been proven to be true.  But it's still a model.   I'm asking you, is there anything physical, an experiment that has been done, might be able to be done (even in theory), or an observation of a distant body that proves beyond a shadow of a doubt that the mass is not a singular point (or ring, or whatever).   
You can get it from the Hawking radiation and gravitational waves will tell you a lot about whether or not there's a structure in there too given how black holes merge and ringdown. But there are other physical reasons why the mass has to be very localised to a small region near the center which is to do with our understanding of the properties of matter.

How can one say that GR is correct beyond the point we can see when there is no data to prove it?   Again, I'm not trying to ask this in a gotcha kind of way.    I just don't understand how mass/energy can fall to a single point in space.   
The least speculative option is GR given how well the other predictions all stand up to scrutiny. And thats my argument, given the success of GR anything that comes afterward has to reduce to GR in the appropriate limit, just like GR reproduces Newtonian mechanics in the appropriate limit. So it may be there's a spacetime crystal or phase transition to another universe inside a black hole or some other exotic thing. Observers are limited to what they can measure about black holes so we would have to hope that subtle distinctions exist between these options to distinguish the new theories predictions from vanilla GR, ie in the gravitational wave signature or some details of the black hole shadow, etc. These are quantities which are now on the cusp of being tested. Exciting times!

I'm not saying I can't understand why according to GR, I certainly could if I just accept that it is true everywhere (like you do), I just find it physically hard to believe because a singularity that is infinite seems like adding infinity+10 more stars shouldn't grow the event horizon, yet apparently it does.  Do you see what I'm saying?
Why should adding mass to a black hole NOT grow the event horizon? More mass means more curvature which means it's more difficult to escape the black hole at larger radii. I don't understand your objection to this point.

radius of event horizon = 2GM/c^2 where G is the gravitational constant, c the speed of light and M mass of the black hole. As M goes up, the radius of the event horizon goes up too.

Edited to add: I re-read your post and think you are mistaking mass for mass-density. The mass of the black hole is finite so M has a well-defined finite value. That mass must all be in a very small (point-like) region at the center of the black hole. This since mass divided by volume gives mass density if that mass is in an extremely small volume the mass density is very high. That mass density is what is finite, not the mass itself at r=0. Hope that helps.

You wouldn't say, that in a way, every large body has an event horizon where you cannot escape it's gravity (ignoring the ability to generate opposing forces, or coming at it with speed)?   Of course, a black hole is not a star, but what concrete example says that what is inside of a black hole is not simply matter in some form that does take up a reasonable amount of space?   
An event horizon is not a physical thing. It's a radius at which the escape velocity is equal to the speed of light.
Every body has an event horizon, it is the radius beyond which the body would need to be compressed to become a black hole. You have an event horizon smaller than a proton. If you were crushed to this radius your body would be entirely within the event horizon and your matter would have sufficient density to become a black hole. In fact, in all stellar modeling schemes you have to check if the radius is smaller than the event horizon defined by the interior mass at all radii inside the star. That's the difference between a star and a black hole a star has a surface which by definition is outside of the event horizon. A black hole has all mass within the event horizon.

So far all you've given examples of are the outside observations and calculations,
Which are all we'll ever have. No signals can get out.

which you admit DO break down at the singularity. 
They do, but that does not affect the horizon structure or the external geometry. Newtonian gravity breaks down at r=0 too, and so do Maxwell's laws. It's why the delta function was invented/discovered.

You don't know what happens even beyond the point where someone has gone from red to dark red to invisible.
Yes, I do. Everything up to the singularity is well defined and understood mathematically. The singularity is not. The outside observations agree with GR predictions. No matter how much you may dislike it, GR has a track record of working well and it does in this case too. It has a long line up of people hoping and praying to shoot it down and would not have lasted as long as it has if it did not work well. Everyone wants to be the guy to beat Einstein but it's proven very difficult to do.

Edited to add: Of course, GR is not the full picture, which would also give back the behavior of mass and density at the singularity. But any theory that replaces it pretty much has to keep all the stuff that GR does right in terms of the external and horizon geometry. It will "reduce" to GR in the appropriate limit. It *must* because GR matches so well with what we observe. There's not really any way around that.

In the ring case, is the singular ring a 2d ring or a ring rotated in 3 space, such that it makes a hollow sphere?
It's a 2D ring in the plane of rotation. There's a more complicated horizon structure, too.

It pains me to say this, but I have been underwhelmed and I went into it with low expectations. The first episode hit a high point for me and I've been pretty critical of the rest. The trip scene was great but the were-lizard dude was equal and opposite. No net gain.

I'm sort of left asking if we really needed this at all. I hope the finale blows the doors off but not holding my breath for that.

There's always Twin Peaks. No, I haven't learned my lesson yet.

Yeah, what ever happened to "Its intuitively obvious to the most casual observer. "

"It is left as an exercise for the reader to prove the effect occurs as stated."

I haven't read it yet, but this is not entirely hypothetical.  Some small organisms on Earth are dominated by things like surface tension of fluids and electrostatic charge.  Unfortunately they can't tell us that that feels like.

Yes it's true. These organisms would have a very different understanding of the cosmos than we would even if they could observe the outside world.

That paper also contains a great example of the size of the beings they consider. A caption reads "Above: They are very tiny" below a blank figure. Effective.

Ah, okay.  One additional question, sil vous plait.  Is it known whether this transformation from virtual to real particle take place when the paired virtual particle crosses the boundary of the event horizon, or once that paired virtual particle is incorporated into the mass of the black hole?
My gut says the best way to answer is that after deltaT has gone by and a particle still exists, the total energy of black hole + infalling doomed particle must be smaller than it was before.

Really it's a good question, and has a very difficult answer, since we're now dealing with the total energy, in the form of the energy momentum tensor, which must be dynamic. Plus the vacuum state is involved too. It's messy and I don't think I can give a better non-technical answer to it. The spacetime curvature has to change ever so slightly because there's less rest energy inside the horizon than there was previously. It's also difficult to answer the next followup question, which will (should?) be "deltaT for who?". I think that must be an observer in free-fall at the same distance from the black hole as the virtual particles came into existence, but it's also difficult to even say where those particle form exactly because of the wave particle duality, how localized are they, etc.

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