Danijel Gorupec

My guesstimation is that it would take about 22 tons of matter + 22 tons of antimatter at the halfway-to-moon distance to make some serous damage on earth. This is based on total irradiation energy equivalent to the energy released in 1000 megaton explosion... 1000 megaton seem quite a lot, but when distributed over the whole earth's disc, I don't think it would be deadly (but I guess some significant damage will be done).

The Space Shuttle had considerably more mass than this, so its explosion (supposing half matter half antimatter composition) would cause serous damage on Earth surface. Possibly global-scale fires.

(It would not event touch the solar system - the sun converts 4 million tons of mater into radiation every second)

26 minutes ago, MigL said:

Intelligent machines depend on the 'bags of protoplasm' having achieved an intelligence level facilitating their construction.
As such, they would be even more scarce ( being equivalent to a subset ).

Not all intelligent life will develop intelligent machines.
Not all will develop space travel.
Not all will be able to communicate with EMR.

Imagine if we had evolved underwater like dolphins/whales.
Or on a gaseous giant planet and floated in the upper atmosphere.
Or silicon based life, on a hot planet.
What kind of challenges would we have developing the technology we take for granted ?

All true, I agree...but the essence of the Fermi paradox ,as I see it, is: if at least one civilization managed to develop a method of interstellar spreading, there is nothing to stop it until it takes the whole galaxy. So it should be here too. (Interestingly, such spreading machines do not even have to be intelligent - they only have to have a 'will' and the ability to spread)

I am not a very optimistic guy, but I still think that, according to our current course, within 200 years we should have self-optimizing machines capable to overrun biological evolution.I don't know what might follow, but I suspect that for a machine, the interstellar travel is not such an unthinkable endeavor as it is for humans.

[Well, because no other civilization seem to be present here, I might speculate that either human-type tech civilizations are very rare, or something very bad will very likely happen to our civilization in next several hundred years..]

I never understand why people continuously consider the future without intelligent machines. Like if it won't happen.

I cannot even imagine an advanced civilization that does not almost exclusively consist of intelligent machines. Machines that copy and redesign themselves in millions of different directions - some large as moonlets, but most as small as sand particles. Enormous amount of them, billions of billions.

This is how I understand Fermi's question: where are those intelligent machines, vast swarms of them that are spreading thought the galaxy in a diffusion like manner (not where are those 'bags of protoplasm' with their rockets)?

6 minutes ago, dimreepr said:

That seems to invalidate the option to abstain, which is a vote.

The problem here is, ones future depends on the performance of those one has no control over, and so is no different to what we have now; it may seem to encourage a less short term thinkspeak but ultimately we're left with the same problems.

 

My proposals would certainly need some refining

However, regarding my second proposal... I actually think that politicians are responsible for the future, even including who replaces them. For example I consider Obama positive and intelligent politician, but I find him unsuccessful about securing continuation if his policies. Maybe he was simply not smart enough to recognize that society tends to spring back... A more extreme example: Marcus Aurelius was considered a smart and wise ruler, yet he secured his son as his successor... shouldn't he 'suffer' for his decision (if he continued to live) by receiving smaller salary?

(But anyway, my proposal is limited to certain number of years - depending on the inertia of the macroeconomic cycles - not more than that.)

Law1 (to combat impulsiveness of common people): referendum questions must come in pairs - each part of the pair is to be composed by opposing proponents. The vote counts only when both questions in the pair are voted adequately.

Law2 (to combat short-aiming policies of politicians): salaries of politicians holding office extend to a period even years after they left the office and depend on measurable performances of the state and society (like GDP, life expectation, etc..)

I too expect the most from solar in short term (20 years). Although I am not nearly as optimistic as Phi for All

In parallel as we are expanding the solar network, we need to improve on other fields: energy storage, energy transport and... agricultural yield. We might also need to improve recycling of solar panels to avoid garbage buildup.

In my opinion, solar is the most plentiful of all renewable resources and thus makes the most sense. The one intrinsic problem with solar, as I see it, is that it uses land (people tend to live near fertile land - so you either need to 'spend' this fertile land for solar, or you must build solar far away from people). Other intrinsic problems with solar is that it is weather dependent and will only work half-day shifts.

I also expect wind energy to continue to grow - it complements solar nicely.

Now the pessimistic part... it really scares me when I look behind and I see some 25 fold energy consumption increase in last 100 years. No known renewable can cope with that. We may hit a development ceiling... While I don't think we need to continue at that rate, even 5 fold increase in next 100 years would be difficult.... The only way to continue our current development pace for next 100 years, as I see it, would be to employ fusion energy. We are however far behind the schedule, imo.

In his chapter 26, volume 2 ( http://www.feynmanlectures.caltech.edu/II_26.html ), Feynman produces an equation that, I guess, shows the x-component of the electric field of a moving point charge... equation (26.6).

He then says that the electric field of a moving charge is 'oblate': its parallel field being somewhat weaker, while its perpendicular field being somewhat stronger. Fine.

In the same chapter, further below, he makes a table of Lorentz transformation of fields (table 26-2):

I would expect the two results match, but I don't see how. According to the transformation table, the x-component of the electric field of a moving point charge should remain unchanged (E'x=Ex), yet according to equation (26.6) the x-component weakens a bit. What am I getting wrong?

7 hours ago, beecee said:

Something worth noting from the article I linked to...https://phys.org/news/2019-06-ten-chernobyl-television-series-artistic.html

6. The divers

 

Thanks for the article link.

Regarding the three divers... I read somewhere (hardly I would be able to find it again) that the three men considered it their duty - two of them were on theirs shifts, while the third one was called for his specific knowledge. I would still consider the act possibly heroic. If it is made 'in vain' does not diminish this. If it is made on the line of duty also does not diminish this.... Interestingly, only recently Ukraine recognized the act: from wikipedia: https://en.wikipedia.org/wiki/Individual_involvement_in_the_Chernobyl_disaster

" Despite severe risk, all three survived the mission, and, in 2018, were awarded the Order For Courage by Ukrainian President Petro Poroshenko."

[BTW, the same wikipedia page mentions another involvement of Aleksandr G. Lelechenko " ...to spare his younger colleagues radiation exposure he himself went through radioactive water and debris three times to switch off the electrolyzers and the feed of hydrogen to the generators..."  Well, if this is true (I am not considering Wikipedia overly reliable) then I would consider it heroic - note that his act was volunteered and not asked for, for the difference]

43 minutes ago, beecee said:

Like I said, I researched as much as I could without leaving the country and found the movie to be pretty well based on fact and accurate on most counts. Did you see the movie?

Unfortunately not (I hope I will soon)... I did not clam you are wrong. I was just surprised how quickly you confirmed all the fact from the movie (It is a long movie, while your words were "Correct and accurate on all counts" - a statement quite opposite to my experience with commercial wide-audience movies. You understand my surprise.)

BTW, I am not sure what this thread is all about, but if it is about discussing how factual is the movie, then you can point out several things that you think might be worth discussion.

7 hours ago, beecee said:

After doing some research and reading up on historical accounts, I have no reason to change my mind....The movie for all intents and purposes, seemed overall pretty well factual where it counts.

Did you use the scientific methods in your research or did you just look for (and found) materials that confirm events in the film?

But why the study - scientific or political reasons? Was there any doubt in scientific community?

2 hours ago, SerengetiLion said:

I was 51 damn years old when I finally wised up.

For some reason, I find this truly remarkable.

1 hour ago, koti said:

For me it was no specific thing, it was a process that took untill I was around 30 years old. In retrospect, I also think that I never believed in God, I just had problems with admitting it to myself and people around me and that changed when I was around 30.

What I learned on the SFN, and what surprised me, is that most atheists are former believers. I, however, never had that 'privilege' - I am what I call a 'native atheist'.

One consequence of never being in a position to abandon a religion is, I guess, that if someone is to ask me why I am an atheist, I would not be very good in giving a rational explanation. I think I would go with an argument of sense and beauty: I just feel, deeply inside, that any idea of God is just too odd, too awkward. Where should I put him? Wherever I tried to put him, he just did not fit.

Guys, how old were you when you stopped believing in God? I wonder if this can happen after 30.

I guess, it might show increased drag (as it rolls around) due to Eddy currents. If the box is wide and large, I don't think the effect would be any spectacular.

Did you have some specific effect on your mind?

1 hour ago, Strange said:

When something falls into a black hole (or when they merge) then the event horizon is actually distorted towards the approaching mass. There is then a "ring down" phase where the event horizon oscillates while it settles down into a (slightly larger) sphere again. But that only tells us about the mass that was outside, not what happens when it is inside.

How can an event horizon ring? Isn't time stopped at the event horizon, and thus for an outside observer it should remain unchangeable? I don't even understand how it can grow.

Thanks beecee, hopefully this weekend I find time to read in more details (both links seem interesting, yet difficult for me).

Anyway, after a quick look at the links, it seems to me that this BH observation might mean more for the theory of accretion disks than for the theory of black holes themselves.

I have few additional questions about the photography:

Any idea what is the approx. mass of the accretion disk relative to the black hole mass? Should I expect it to be 'paper-thin' (like Sautrn's rings) or does it have a substantial thickness? What is the density of the accretion disk near its 'middle' region - like that of water? Or more? Or less?

What do colors/shades on the photo show - radiation intensity or radiation wavelength?

3 minutes ago, Strange said:

It is from the accretion disk. M87 is a fairly active black hole - see the massive polar jets in the second image in that Forbes article.

Great photo - thanks.

Accretion disk! I thought it is some sort of occultation that was imaged (I assumed this because of all the talk regarding the shape of its shadow)... If it is accretion disk, then I guess it is lucky that it is angled the way to show us the black middle.

What is the size of the black thing? I couldn't find this data in the link provided by Strange.

What is the source of the background microwave radiation? Seems huge.

12 minutes ago, studiot said:

Does this help?

Actually yes; thank you. It introduces the concept of 'evolution of energy' which I find more intuitive than the 'energetically favorable configuration'.

But I guess there is some misalignment in your answer and my question - you are talking about 'energetically favorable process', while I ask for 'energetically favorable configuration'. I can guess, from your answer, that the 'energetically favorable configuration' could mean that a system reached a state where there is no more net evolution of energy - could this be right?

(Yes, I had to write 'isolated system' instead of 'closed system' - I guess i my language we use the same term for both things).

AI is limited by laws of physics - it cannot do God-like things, if this is what you had in mind.

Maybe there are other limitations that we are not aware of (for example, maybe extreme intelligence is not stable in single personality - maybe personalities spontaneously split. I don't think it is like that, but I don't know of any proof against it.)

Edit: typo

A quickie... What does the term 'energetically favorable configuration' means? Does it have any strict meaning at all?

One might say, for example: "magnetic domains will set into an energetically favorable configuration" (but my question is general, not about magnetic domains in ferromagnetic materials).

(If it means 'lowest possible energy' then I guess that closed systems cannot have 'energetically favorable configuration' as the energy there is conserved)

1 hour ago, beecee said:

Perhaps the point you are trying to make is the forthright "apparent" abrasive nature of people such as Hitchens and Dawkins. Personally, I see the more "dulcet tones" of the likes of the late great Carl Sagan as far more productive.

Not the topic her, but yes, it does bother me. It seems that people are associating atheism with these prominent and men - but, sadly, mostly to the aggressive part of their image... I noticed that I started to feel bad about revealing my own atheism, or if I am forced to reveal, I quickly say "atheist, but not anti-theist".

1 hour ago, MigL said:

Even 'offensive' people say decent things.
And while he may be anti-religion, he is NOT anti-religious people.
IE don't be so sensitive.

Hmm... but isn't it that you should be explaining this to new forum visitors? They will be judging this forum by its quotation choice. They will judge that this is a fighting forum and will take the fighting stance (some of them happily and readily). They won't make their judgement by what is quoted, but by who said it.... This is the practical side of my reasoning against the quote.

Yes, I know I am exaggerating (very few people will actually read the quote... and if we also write the author's name in a very fine print...)

1 hour ago, Phi for All said:

I think having a mission statement focusing on reasoned openmindedness from a man who was sometimes considered over-passionate about science is appropriate here. Besides, we can include something to the effect that, if you think we chose Hitchens to offend you, you're all wrong. We can use emojis to further demonstrate our non-offensiveness . 

If this can be done, it would be much better

But my advice to the owner of the forum remains the same.