For Questions That Don't Merit Their Own Thread

[StrandedonEarth]

9 hours ago, monophonic said:

So, where can we get with that?

Depends how fast you want to get there, or how much acceleration can actually be applied…

[SunlitZelkova]

13 hours ago, sevenperforce said:

A fusion candle is thusly named because it is burnt at both ends, not unlike how a candle can be. You grab a large iron asteroid, reinforce it quite thoroughly, and hollow it out. Build city-sized fusion engines at both ends and giant intakes in the center, and then carefully sink it into a gas giant. Uranus would be best for this (let's leave jokes about sinking something into Uranus aside) because it has the lowest rotation speed of any giant in our system and the lowest mass and thus requires the least effort to move around. As the asteroid sinks into Uranus, fire up the intakes to suck in the Uranian atmosphere and ignite the lower fusion engine, holding the asteroid aloft on a column of its own flame. Then fire up the other engine, balancing appropriately, and start flying. It's a slow and steady process, but it's doable.

You can then use its gravity to come in and grab Earth and haul it off to a new home solar system. And you're carrying your own mini-sun with you, which isn't the worst of all possible arrangements.

Thanks for this! I was actually thinking of asking around here for Dyson sphere level mega-engineering projects, so I’m glad to know about this now.

[magnemoe]

12 hours ago, monophonic said:

Doable until hot exhaust ingestion causes a flameout, that is. Well, I guess that is what's called "engineering details."

But how much delta-V does one Uranus give with a one Earth payload? A quick jot in a spreadsheets gave me 2938455,386 m/s/s. Lot's of inaccuracies there, not to mention probable mistakes, but WOW! Of course you'll be spending majority of that keeping the candle in place, as you'll need to offset the outward thrust and gravity of Uranus the fuel tank. Let's throw in a round divide by three or so for that and call it an even

One Million Meters per Second Squared!
Insert Dr. Evil meme

So, where can we get with that?

1000 km/s or .00333 c. Not very fast, An decent and huge pulse nuclear ship would be more than 10 times faster and don't require new science. An serious engineering challenge but nothing compared to using Uranus an an rocket  
The candle is likely to need active support to keep together, you run an heavy mass in an circular magnetic track like an particle accelerator but with an freight train of magnets. This create an counter pressure stronger than any material. 
Downside is that any fail modes is in the kiloton range for the small scale. And this has to work for over 1000 years, yes you can take modules offline but idea has issues. 
Still you are moving planets.  Now you teraformed Mars and probably Venus and you have part of an dyson swarm so you take this with you. 

[JoeSchmuckatelli]

How do researchers know they're getting actual data or 'corrected data'?

 

Question comes from a recent paper on the 'Crisis in Cosmology' where the researchers had to first figure out what the 'standard correction' was, and then take that out to make their inferences.  The 'standard correction' in this case was making sure the spectra aligned with LCDM theory.

Is there a way to get observatories to just give you what the telescope is seeing - or do they all control the data and only put out what they want to put out?

(To be fair, as far as I can tell, the researchers in question were using other folks' published data - so it may have been the clients of the telescopes applying the 'correction' rather than the telescope it/themselfs.

[kerbiloid]

8 hours ago, JoeSchmuckatelli said:

Is there a way to get observatories to just give you what the telescope is seeing - or do they all control the data and only put out what they want to put out?

If take a look at the raw data (were available in internet a decade ago), you will see that the raw data include negative values and other such things, and aren't edible without mathematical correction based on previous observations.

Any theory is just a temporary tool. It becomes obsolete when you have to sort out too much data.

[Jacke]

On 12/13/2022 at 4:11 AM, sevenperforce said:

A fusion candle is thusly named because it is burnt at both ends, not unlike how a candle can be. You grab a large iron asteroid, reinforce it quite thoroughly, and hollow it out. Build city-sized fusion engines at both ends and giant intakes in the center, and then carefully sink it into a gas giant. Uranus would be best for this (let's leave jokes about sinking something into Uranus aside) because it has the lowest rotation speed of any giant in our system and the lowest mass and thus requires the least effort to move around. As the asteroid sinks into Uranus, fire up the intakes to suck in the Uranian atmosphere and ignite the lower fusion engine, holding the asteroid aloft on a column of its own flame. Then fire up the other engine, balancing appropriately, and start flying. It's a slow and steady process, but it's doable.

You can then use its gravity to come in and grab Earth and haul it off to a new home solar system. And you're carrying your own mini-sun with you, which isn't the worst of all possible arrangements.

Larry Niven in his 1976 SF novel A World Out of Time had something like that: a massive fusion engine floating in the atmosphere of Uranus to maneuver the ice giant in very careful flybys to move the Earth.

https://en.wikipedia.org/wiki/A_World_Out_of_Time

 

[JoeSchmuckatelli]

This may be obvious to some - but I just want to confirm something.

Generally speaking, if you convert an element into a plasma, once the heat dissipates, the plasma can revert back to the original element.  Hoping that is correct.

So... if you contain a plasma in an electromagnetic field, the neutrons can escape that field because they are not charged particles.  So... am I correct in assuming that if you took Methane for instance and heated it to a plasma state, contained that plasma in an electromagnetic field for long enough for all the neutrons to escape... when it cooled, would you be left with just Hydrogen?

[kerbiloid]

https://en.wikipedia.org/wiki/Plasma_recombination

It can, unless the lightweight electrons had escaped. Otherwise the ions and electrons will divorce and re-marry to surrounding matter electrons and ions respectively.

36 minutes ago, JoeSchmuckatelli said:

if you contain a plasma in an electromagnetic field, the neutrons can escape that field because they are not charged particles. 

The neutrons don't escape from nuclei on ionization. They stay in the nuclei, unless the plasma was created by nuclear fission (say, caused by fusion, D + T → He + n).
So, as the plasma is an ionized state of the matter, the neutrons aren't part of the plasma. They are a neutron gas mixed to this plasma.
This (neutron) gas doesn't interact with magnetic field and isn't aware of its presence, it's just a monoatomic gas.
https://en.wikipedia.org/wiki/Neutronium

36 minutes ago, JoeSchmuckatelli said:

would you be left with just Hydrogen?

Just with helium and remains of the original mixture, otherwise where had the neutrons appeared from?

Edited December 21, 2022 by kerbiloid

[JoeSchmuckatelli]

15 minutes ago, kerbiloid said:

otherwise where had the neutrons appeared from?

Hydrogen does not have neutrons (from what I remember from 35 years ago).

16 minutes ago, kerbiloid said:

They are a neutron gas mixed to this plasma.

That's cool - learning something new today!

 

[kerbiloid]

5 minutes ago, JoeSchmuckatelli said:

Hydrogen does not have neutrons

D and T have, and ¹H can produce them on fusion.

But if there are no neutrons... then there arre no neutrons to escape.

[Jacke]

1 hour ago, JoeSchmuckatelli said:

So... if you contain a plasma in an electromagnetic field, the neutrons can escape that field because they are not charged particles.  So... am I correct in assuming that if you took Methane for instance and heated it to a plasma state, contained that plasma in an electromagnetic field for long enough for all the neutrons to escape... when it cooled, would you be left with just Hydrogen?

A plasma has atoms stripped of some or all electrons to make all particles charged as well as energetic.  To remove Neutrons from the nuclei takes massively more energy, as only seen momentarily in the centres of exploding hydrogen bombs or in the case of a very energetic particle (like an accelerated Proton) that can hit a nucleus and knock a Neutron out of it.  Plasmas won't have free Neutrons just from being heated, but need to be confined, superheated to massive levels, and perhaps bombarded with even more energetic particles to change the nuclei.

[JoeSchmuckatelli]

8 hours ago, Jacke said:

Plasmas won't have free Neutrons just from being heated, but need to be confined, superheated to massive levels

Yeah - it's funny, but  if I ever studied plasma in college I certainly don't remember much more than 'it exists as a state of matter'.  Prior to the instant discussion of fusion my most recent reading had to do with million degree intergalactic plasma. 

I hadn't heard of neutrons being able to escape until I saw the video on how Tokamak reactors work.  

So I'm basically trying to get an image in my mind for how plasmas work... (Might have to start googling 'magnetar and plasma'!)   This goes back to the question I asked back when we were talking about intergalactic plasma about whether the plasma state was unique or an actual state of matter for a given element, i.e. can oxygen have a liquid, gaseous and plasma state that regardless of state it is always oxygen - or does entering the plasma state do something to the elemental particles such that once a plasma, given the correct circumstances it might precipitate out to a more basic element when it cools below the plasma threshold. 

All interesting stuff! 

[kerbiloid]

Plasma is nothing but partially or completely ionized atoms.
The chemical element is defined by the proton number in the nucleus, it doesn't change on ionization.
The nuclear and elemental composition is not affected by plasmification or plasma recombination.
The chemical composition is affected, but just because the molecules may get broken. The oxygen is still oxygen, but it can get atomic rather than molecular.

The space plasma stays plasma because it's very... undense. So, the ions and electrons meet rarely, and the recombination process runs slowly.
Or because the plasma cloud is too hot (or heated), so the electrons move too fast to be captured by ions.

The neutrons don't have charge, and thus electron clouds.
So, they can't be ionized and become plasma. Neutrons are always gaseous (unless it's inside a pulsar).

Edited December 22, 2022 by kerbiloid

[K^2]

14 hours ago, JoeSchmuckatelli said:

So... am I correct in assuming that if you took Methane for instance and heated it to a plasma state, contained that plasma in an electromagnetic field for long enough for all the neutrons to escape... when it cooled, would you be left with just Hydrogen?

If your temperature is high enough for atoms to come apart into protons and neutrons, we're not talking plasma anymore.

[JoeSchmuckatelli]

6 minutes ago, K^2 said:

If your temperature is high enough for atoms to come apart into protons and neutrons, we're not talking plasma anymore.

Yeah - I can see the shape of my 'over the holidays' reading list coming into view!

[Jacke]

Plasmas are used because all the particles in them are charged, therefore magnetic fields can be used to confine and direct the material.  However, because there's so little material, it's still effectively a good vacuum.

[sevenperforce]

On 12/20/2022 at 11:41 PM, JoeSchmuckatelli said:

Generally speaking, if you convert an element into a plasma, once the heat dissipates, the plasma can revert back to the original element.  Hoping that is correct.

So... if you contain a plasma in an electromagnetic field, the neutrons can escape that field because they are not charged particles.  So... am I correct in assuming that if you took Methane for instance and heated it to a plasma state, contained that plasma in an electromagnetic field for long enough for all the neutrons to escape... when it cooled, would you be left with just Hydrogen?

As others have said, mere ionization of atoms into plasma is nowhere near the amount of energy necessary to strip neutrons out of the nucleus. The nuclear-strong interaction holding a nucleus together, a subset of the color force, is VASTLY stronger than the electromagnetic force keeping the electrons close to the nucleus.

It's not really correct to say that plasma "can revert back to the original element" once the heat dissipates, because the plasma was never anything other than the original element.

I was at an adult beverage establishment last night with neon lamps. Those lamps contain atoms of neon gas. Each of these atoms contains 10 neutrons, 10 protons, and 10 electrons.

The protons and neutrons are held together in a nucleus by the nuclear strong interaction (represented in red). Ordinarily, the strong positive charges of all the protons would push them apart via the electrostatic force (also known as the Coulomb force, represented here in blue), but the nuclear strong interaction is 137 times stronger than the electrostatic force, so the protons are quite happy to stay snug inside the nucleus with all the neutrons.

The electrostatic force is quite good, however, at keeping the negatively-charged electrons close to the positively-charged nucleus. Here, I've depicted the neon atom's ten electrons as if they are in three concentric rings, representing the 1s orbital, the 2s orbital, and the 2p orbital, although in reality these orbitals are not rings at all.

Spoiler

Here's what the orbitals actually look like. The shaded region represents the area through which the electrons can oscillate. The orbital shapes and locations and sizes are to scale.

Those are, from left to right, the 1s orbital, the 2s orbital (which you may observe has two regions within which to oscillate separated by an empty region), and the three 2p orbitals (one in the x-axis, one in the y-axis, and one in the z-axis). Note that the 2s orbital, here, is spherically symmetric; I'm representing it with this shading to show that there is an internal and external region. All five of these orbitals can hold two electrons each, one with up spin and one with down spin.

The orbitals all overlap, so a neon atom "looks" like this, if you add the electrons one pair at a time (note that the nucleus is decidedly NOT to scale):

You can imagine a cutaway looking something like this:

Before the neon lamp is switched on, all of the neon atoms are just bouncing around rather aimlessly in the tube:

When those neon lamps are switched on, a strong electrical current runs through the gas, strong enough to rip one or two electrons free of each host atom via the Townsend process. They do not, however, rip all of the electrons free; they merely need to free enough electrons to maintain a clean plasma path for the electrical current, and then the neon lamp will glow merrily. The atoms themselves haven't moved all that much; it's the much lighter electrons that are doing all of the zipping about:

This is now a plasma. Thanks to all of the free electrons, what was formerly an inert gas is now electrically conductive and will react to magnetohydrodynamic forces.

_{Technically, this should show the inner electrons missing, not the outer electrons, because the inner electrons will actually move up to occupy the empty orbitals due to quantum excitation states. But whatever.}

However, you'll note that all of the atoms are still here. Just because they've lost an electron or two doesn't make them no longer atoms. Even if the plasma was so energized that literally all of the electrons were stripped away, each nucleus would remain completely intact, held together firmly by the strong nuclear interaction. None of the protons or neutrons are going to "jump" from one atom to another.

You need much, much higher energies to start ripping protons and neutrons out of an atom.

There is a hypothetical "plasma" called a quark-gluon plasma, where the nuclei of atoms have been compressed together so much that the protons and neutrons begin breaking apart into quarks, which "swim" freely between residual nuclei much like the electrons in an ordinary plasma. But a quark-gluon plasma would require energies far greater than even those at the center of a star. The only known quark-gluon plasma was during the Big Bang, when that was the entirety of the universe. There are some hypotheses that the centers of neutron stars contain a quark-gluon plasma kept from collapse by fermion degeneracy pressures, but we don't know for sure.

[JoeSchmuckatelli]

4 hours ago, sevenperforce said:

mere ionization of atoms

Okay I'm on my second read through... And thanks! 

One of the things I love about this board - details! 

Still juggling.  When I've had a chance to think about everything I'll ask for more - but, again, thank you and the others who have taken the time to reply to what I thought was a 'quick question' 

[JoeSchmuckatelli]

If a game company is still writing their net (&server) code for IPV 4, how does that affect lag and desync for people in countries where IPV 6 has been implemented?

[K^2]

2 hours ago, JoeSchmuckatelli said:

If a game company is still writing their net (&server) code for IPV 4, how does that affect lag and desync for people in countries where IPV 6 has been implemented?

It generally shouldn't. Usually, you're being routed through the same gateways, so in practice, there isn't too much difference. And if the servers are cloud-hosted, that will get translated to IPv4 anyways. There might be some issues if one of the players is hosting, and there's a mix of IPv4 and IPv6 addresses being used, but that has more to do with NAT at home router level than anything else. Outside of outright bugs in code meant to handle both IPv4 and IPv6 connections, I can't think of any meaningful differences, but maybe I'm forgetting something.

[JoeSchmuckatelli]

2 minutes ago, K^2 said:

It generally shouldn't. Usually, you're being routed through the same gateways, so in practice, there isn't too much difference. And if the servers are cloud-hosted, that will get translated to IPv4 anyways. There might be some issues if one of the players is hosting, and there's a mix of IPv4 and IPv6 addresses being used, but that has more to do with NAT at home router level than anything else. Outside of outright bugs in code meant to handle both IPv4 and IPv6 connections, I can't think of any meaningful differences, but maybe I'm forgetting something.

Huh.  The people complaining about the net code of a certain game seem convinced that is the issue. I'd never heard anything like that.  The alternative explanation includes CGNAT on IPv6 'closing the hole' in the firewall and the gamer's client losing connection with the server... Which would not happen in Ipv4. 

 

All this is Martian to me - but I am starting to see shapes in the mist (to mix metaphors) 

[K^2]

NAT definitely works differently in IPv4 vs IPv6, so yeah, I can see how net code designed to work with IPv4 NAT might be a problem here.

For a little bit of a context, NAT is short for Network Address Translation, and any additional letters around it point to different ways it can be accomplished. I'm not an expert in how any of that works, but the gist is that under IPv4, because there aren't that many addresses (a little over 4 billion total combinations), your router at home gets its own WAN (wide area network) address, and any computers connected through it have to share it. So, maybe your PC is connected to the router directly, and your laptop and your cell phone are on WiFi on that same router - from perspective of greater internet, they all share an IPv4 address. But for your router to talk to each device, it assigns its own LAN (local area network) address to each device.

So when you ask for a page of this forum, the server sends it back with your router's address, and your router has to figure out if you requested it from your PC, laptop, or cell phone (in the above example). When you are connected through TCP (which is used for all web requests), the router can look at additional information in the packet to match response to a request, and it knows which LAN address to forward it to.

This gets complicated with games, however. Not only are they using the UDP, but you might also be the one hosting the server. When another player connects to you, the very first packet telling that they want to connect arrives at your router, and without some additional mechanism, your router has no idea where to send it to. Something in the game has to tell the router that you'll be expecting a request and where it should be forwarded. There are a number of different ways this can work (including IP spoofing in some older UDP games...) and none of it is completely fool proof.

IPv6 is different. Because there are a lot of addresses available, your router doesn't just get an address, it gets a range. It assigns sub-ranges to devices on the LAN, so if you publish your IPv6 when hosting a game lobby, that address points not just to your router, but to the specific device you used to host the game. However, even here things aren't smooth, because of course it couldn't be simple, and you actually get several different IPv6 addresses assigned, and some of them are permanent, and others are temporary, and you're supposed to use them in different situation because security. And if you simply copy-pasted your old IPv4 code, you're probably publishing the wrong IPv6 address, which means at some point your connection might go away, etc.

It all gets pretty complex, and this is why dev ops people and network engineers are paid good money.

[SunlitZelkova]

Is belief in alien visitation/UFOs, cryptozoology, and other conspiracy-related pseudosciences a product of the same psychological mechanism that induces basic science denialism?

I.e. is “the scientists lie, this fantastic thing is actually happening” identical to “the scientists are [just] lying”?

[DDE]

4 minutes ago, SunlitZelkova said:

Is belief in alien visitation/UFOs, cryptozoology, and other conspiracy-related pseudosciences a product of the same psychological mechanism that induces basic science denialism?

I.e. is “the scientists lie, this fantastic thing is actually happening” identical to “the scientists are [just] lying”?

I would would strongly disagree with the wording of the question. For starters, alien visitation and cryptozoology afford room for an iteration where Da Guberment isn't hushing anything because they're don't know much more than the average Joe - e.g. the aliens are hiding from them too.

Then you have the variation in that these theories do not always correlate with anti-intellectual / anti-intelligentsia / anti-science views; usually the conspiracy involves not all individual scientists but Big Science and/or Da Guberment oppressing individual scientists. The tendency of such theories to be promoted by "truth-seeking" / "dissident" faux-scientists in labcoats touting crooked credentials is indicative, I think, of not all scientists getting written off as in on the conspiracy. There's also the angle of the phenomenon being "too advanced" for scientists who don't use the theory-maker's esoteric methods of knowledge acquisition, and so they deny it out of ignorance rather than malicious conspiracy.

[kerbiloid]

4 hours ago, SunlitZelkova said:

Is belief in alien visitation/UFOs, cryptozoology, and other conspiracy-related pseudosciences

, like the:

• Stones falling from the skies.
• Continents crawling along the planet
• Huge (twin) landmass at the "opposite" side of the planet, when every educated man knows that it's a disk with Jerusalem in the middle, surrounded by ocean, and (the educated man) is seeking for the Prester John's Kingdom which definitely exists somewhere over here.
• Planets moving not along the perfect circles, regardless of gravity which makes heavy things fall because it is in their nature.
• Small pieces of hot water quickly colliding each other, rather than obvious heat substance which can be poured from one body into another one.
  (Just can't imagine how this stupid idea could be thought out.  Colliding pieces of water making it hot, just try to imagine this... )
• Flies having six legs while even Aristotle, whose unspeakable wisdom is not to be questioned, clearly wrote that it has eight.
• Flying machines heavier than air, which can fly horizontally instead of falling down.
• Venomous mammals laying eggs.

P.S.

4 hours ago, SunlitZelkova said:

cryptozoology

Australia.

4 hours ago, SunlitZelkova said:

alien visitation/UFOs

South America, XV century.

Edited December 30, 2022 by kerbiloid