For Questions That Don't Merit Their Own Thread

[kerbiloid]

Spoiler

Escape Bags.
3 crews inside the cabin for 1.
Bonus feature: keeping the pressure while pressurized.

 

1 hour ago, tater said:

Seems like the officers are more likely to get out, the rest of the crew... not so much.

Others push from below.

[DDE]

4 hours ago, tater said:

How many decks? What's the crew complement, 80?

Three, perhaps four.

I've tracked down the origin of @DerekL1963's screenshot: 

https://youtu.be/7j3x9870y04?t=1585

[cubinator]

What would be the best way to get a message to 99.99% of all humans?

[kerbiloid]

10 hours ago, DDE said:

https://youtu.be/7j3x9870y04?t=1585

08:15 The onboard brigade of painters?

16:15 Now I get why the submariners' height is limited. But what if make longer bar legs?

16:30 The wooden parts are so cozy.. Aren't they that what was teared off and thrown overboard before the battle begins, in early XX? (See Novikov-Priboy's book.)

17:00 Rabbit cells? Do they herd them?

17:40 A wine cellar - and a full-time sommelier to serve this right.
Btw, has anyone of you provided your Martian ship with the wine cellar?! Take the master-class from professionals.

***

31 minutes ago, cubinator said:

What would be the best way to get a message to 99.99% of all humans?

Spoiler

 

Edited September 5, 2020 by kerbiloid

[JoeSchmuckatelli]

8 hours ago, cubinator said:

What would be the best way to get a message to 99.99% of all humans?

Have the death star blow up the world? 

Message: time to die 

[DDE]

31 minutes ago, JoeSchmuckatelli said:

Have the death star blow up the world? 

Message: time to die 

That would be half the world, at best. The other half won't have time to respond.

[cubinator]

2 hours ago, DDE said:

That would be half the world, at best. The other half won't have time to respond.

"As if millions of voices cried out in terror, and were suddey silenced."

I think the Bat-Circle projected onto the Moon is the better choice. 

[ARS]

10 hours ago, cubinator said:

What would be the best way to get a message to 99.99% of all humans?

Want to send a message to the whole Earth that you're awesome, powerful and evil? Or maybe you just want to show to absolutely everyone on this planet about how much you care for your beloved? Just fire up your biggest laser cannon or longest-range missiles and use them to deface the Moon by blasting your face on Lunar surface or [INSERT YOUR MESSAGE HERE] onto it, just for the lolz. After all, the Moon has no weather or pesky tourists to mess it up... so any mark left on it, even if it's just etched into the dust, will probably remain there until the Moon itself is destroyed (or any lucky space objects impacting Moon's surface). Your message will be set in stone, literally (pun intended) pardon the cliché

[JoeSchmuckatelli]

If space and time are intertwined, and mass compresses space and time, do we say that the speed of light is the same in the presence of a massive object as it is in the intergalactic void because the ruler has changed? 

[Nightside]

ok, which one of you knuckleheads...?

https://www.thedrive.com/the-war-zone/36096/airline-pilots-landing-at-lax-report-a-guy-in-jetpack-flying-alongside-them-on

 

[SOXBLOX]

1 hour ago, JoeSchmuckatelli said:

If space and time are intertwined, and mass compresses space and time, do we say that the speed of light is the same in the presence of a massive object as it is in the intergalactic void because the ruler has changed? 

Yes, we do. All observers measure the speed of light to be the same, regardless of what their circumstances.

 

46 minutes ago, Nightside said:

ok, which one of you knuckleheads...?

https://www.thedrive.com/the-war-zone/36096/airline-pilots-landing-at-lax-report-a-guy-in-jetpack-flying-alongside-them-on

 

I love that website! 

[magnemoe]

On 9/5/2020 at 5:43 PM, ARS said:

Want to send a message to the whole Earth that you're awesome, powerful and evil? Or maybe you just want to show to absolutely everyone on this planet about how much you care for your beloved? Just fire up your biggest laser cannon or longest-range missiles and use them to deface the Moon by blasting your face on Lunar surface or [INSERT YOUR MESSAGE HERE] onto it, just for the lolz. After all, the Moon has no weather or pesky tourists to mess it up... so any mark left on it, even if it's just etched into the dust, will probably remain there until the Moon itself is destroyed (or any lucky space objects impacting Moon's surface). Your message will be set in stone, literally (pun intended) pardon the cliché

The problem is that 99.99% is all except 700.000 people. Guess its more than 700.000 babies and toddlers who would not understand anything of that. 
 

[JoeSchmuckatelli]

58 minutes ago, SOXBLOX said:

Yes, we do. All observers measure the speed of light to be the same, regardless of what their circumstances.

 

...

So... if we say then, that another galaxy is x light years away from the Earth... that's not really an absolute measure of distance... I can't multiply 186,000 miles/second to get a number of miles that would mean anything - i.e. two 500 ly away galaxies might not actually be equidistant from the Earth - the light from one might have to pass through a relatively dense part of the universe, whereas the light from the other goes through a void?

Edit: although (brain twist) maybe it is?

Edited September 7, 2020 by JoeSchmuckatelli

[SOXBLOX]

18 minutes ago, JoeSchmuckatelli said:

So... if we say then, that another galaxy is x light years away from the Earth... that's not really an absolute measure of distance... I can't multiply 186,000 miles/second to get a number of miles that would mean anything - i.e. two 500 ly away galaxies might not actually be equidistant from the Earth - the light from one might have to pass through a relatively dense part of the universe, whereas the light from the other goes through a void?

Gravitation won't slow the light down, but it will distort the path (or rather, it distorts the space through which the light travels). Because of this, the path light travels is longer than one would expect if the space were flat. Of course, the distance in curved space is the actual distance to the object, so if you measure 500 LY, it is 500 LY away. The big thing is, the ruler is always correct, though not all reference frames will agree on the length of an object or the distance between two points.

I am doing a miserable job of "explaining" this. Please forgive me.

[JoeSchmuckatelli]

9 hours ago, SOXBLOX said:

Gravitation won't slow the light down, but it will distort the path (or rather, it distorts the space through which the light travels). Because of this, the path light travels is longer than one would expect if the space were flat. Of course, the distance in curved space is the actual distance to the object, so if you measure 500 LY, it is 500 LY away. The big thing is, the ruler is always correct, though not all reference frames will agree on the length of an object or the distance between two points.

I am doing a miserable job of "explaining" this. Please forgive me.

This is one of those things I can't just learn once.  I 'know' the answer - but again, it's such a brain twist I have to keep revisiting the concept. 

 

Here's a weird question - so what is time, then, other than the movement and curving of space? Does it have any independence from space or does Einstein have them inextricably entertwined? 

[kerbiloid]

In addition. If draw a 4d trajectory of a material point, it may have any repeatable x,y,z values, but no repeatable t.

 

[SOXBLOX]

1 hour ago, JoeSchmuckatelli said:

Here's a weird question - so what is time, then, other than the movement and curving of space? Does it have any independence from space or does Einstein have them inextricably intertwined? 

Oh, drat.

@kerbiloid's description is correct, but it doesn't say what time is. He's saying you can run in circles in space, but you can't return to a previous point in time.

Here's an analogy which helped me.

Joe and Bob are test drivers for a car company. Joe gets the job of test-driving a most impractical car, which always drives at its top speed of 100 mph. The test track is 10 miles long, runs due east-west, and is wide and flat. Bob looks at the recorded data about the duration of each test drive. They should all be 6 minutes long, since the vehicle moves at 100 mph, but he sees that the last few are much longer. 6.5, 7, or even 7.5 minutes. What happened? Joe has an explanation. The sun was setting, and as he was driving west, it was in his eyes. So, he drove the last few, anomalous runs at an angle, not due east-west, but pointed slightly south. Because of this, he was sharing some of his 100 mph motion with the north-south direction, leaving less of his 100 mph for the east-west direction.

Now, if you realize that motion can be shared between dimensions, you will have picked up one of the core insights of special relativity. The trick is to realize that one can share motion between time and space dimensions as well. Actually, most of our motion in the universe lies in the time dimension. We are all moving through time, because you can see changes happen over a period or duration. We are moving at light-speed through time, but when we move in space, we borrow some of that motion. Thus, not all observers have the same clock rate when you compare them; some observers are moving from some other observer's perspective.

(Light does not experience the "flow" of time; it has no motion in time because it moves at light-speed through space.)

As for what time is, I can't help you. There are some ideas out there. One is that it has to do with the increase of entropy, and another is that our universe is actually in motion within another dimension, moving in a direction distinct from the three spatial directions. That direction, or dimension, would be time. IDK. Bit isn't it fun to accidentally run into one of the most important questions in theology, philosophy, and physics all at the same time? I love it!

Edited September 7, 2020 by SOXBLOX

[SOXBLOX]

Robot guard dogs at Nellis AFB? Can I have one?

 http://thedrive.com/the-war-zone/36229/the-air-force-just-tested-robot-dogs-for-use-in-base-security

Edited September 7, 2020 by SOXBLOX

[kerbiloid]

Three legs?!

Spoiler

A houndeye.

Spoiler

Hasn't anybody seen such structure near the Nellis?

Spoiler

 

[K^2]

4 hours ago, SOXBLOX said:

He's saying you can run in circles in space, but you can't return to a previous point in time.

Which isn't actually correct. Closed timelike curve (CTC) is a feature of GR. Albeit, there is CTC conjecture stating that stable metric allowing for CTC cannot arise from positive definte energy density. Meaning, you need at least some negative energy to go back in time. Two notable pounts here are that it is a conjecture, meaning no complete proof exists, and that it only applies to stable solutions. Unstable solutions to Einstein Field Equations allowing for CTC are known. Naked singularity case of Kerr metric is best known example. So while we're pretty sure you can't create anything stable that permanently allows time travel, catastrophic events allowing for brief window are a definite possibility. Parameters for such hypothetical event are not known, but if Kerr case is anything to go by, something like black hole collision at a minimum.

[SOXBLOX]

Just now, K^2 said:

Which isn't actually correct. Closed timelike curve (CTC) is a feature of GR. Albeit, there is CTC conjecture stating that stable metric allowing for CTC cannot arise from positive definte energy density. Meaning, you need at least some negative energy to go back in time. Two notable pounts here are that it is a conjecture, meaning no complete proof exists, and that it only applies to stable solutions. Unstable solutions to Einstein Field Equations allowing for CTC are known. Naked singularity case of Kerr metric is best known example. So while we're pretty sure you can't create anything stable that permanently allows time travel, catastrophic events allowing for brief window are a definite possibility. Parameters for such hypothetical event are not known, but if Kerr case is anything to go by, something like black hole collision at a minimum.

*facepalm*

I concede the point! I ignored the possibility of time travel because it is practically, in the literal sense of the word, impossible, since we ain't got no negative mass.

[JoeSchmuckatelli]

5 hours ago, SOXBLOX said:

Oh, drat.

@kerbiloid's description is correct, but it doesn't say what time is. He's saying you can run in circles in space, but you can't return to a previous point in time.

Here's an analogy which helped me.

Joe and Bob are test drivers for a car company. Joe gets the job of test-driving a most impractical car, which always drives at its top speed of 100 mph. The test track is 10 miles long, runs due east-west, and is wide and flat. Bob looks at the recorded data about the duration of each test drive. They should all be 6 minutes long, since the vehicle moves at 100 mph, but he sees that the last few are much longer. 6.5, 7, or even 7.5 minutes. What happened? Joe has an explanation. The sun was setting, and as he was driving west, it was in his eyes. So, he drove the last few, anomalous runs at an angle, not due east-west, but pointed slightly south. Because of this, he was sharing some of his 100 mph motion with the north-south direction, leaving less of his 100 mph for the east-west direction.

Now, if you realize that motion can be shared between dimensions, you will have picked up one of the core insights of special relativity. The trick is to realize that one can share motion between time and space dimensions as well. Actually, most of our motion in the universe lies in the time dimension. We are all moving through time, because you can see changes happen over a period or duration. We are moving at light-speed through time, but when we move in space, we borrow some of that motion. Thus, not all observers have the same clock rate when you compare them; some observers are moving from some other observer's perspective.

(Light does not experience the "flow" of time; it has no motion in time because it moves at light-speed through space.)

As for what time is, I can't help you. There are some ideas out there. One is that it has to do with the increase of entropy, and another is that our universe is actually in motion within another dimension, moving in a direction distinct from the three spatial directions. That direction, or dimension, would be time. IDK. Bit isn't it fun to accidentally run into one of the most important questions in theology, philosophy, and physics all at the same time? I love it!

Alright - so just going back to xyz coordinates - let's say that I had a second-series (prequel) Star Wars FTL drive (almost instantly get to where you want to go, unlike the original trip taken in the Millennium Falcon) and wanted to visit another galaxy, far, far away... 

Is there any real way to predict its physical location today?  Because if the light we see today from two different galaxies can take different paths that both last 500, 000 years, but be  wildly different 'straight line' distances from the Milky Way today... How could you know you would arrive at your destination and not just somewhere random? 

32 minutes ago, K^2 said:

Which isn't actually correct. Closed timelike curve (CTC) is a feature of GR. Albeit, there is CTC conjecture stating that stable metric allowing for CTC cannot arise from positive definte energy density. Meaning, you need at least some negative energy to go back in time. Two notable pounts here are that it is a conjecture, meaning no complete proof exists, and that it only applies to stable solutions. Unstable solutions to Einstein Field Equations allowing for CTC are known. Naked singularity case of Kerr metric is best known example. So while we're pretty sure you can't create anything stable that permanently allows time travel, catastrophic events allowing for brief window are a definite possibility. Parameters for such hypothetical event are not known, but if Kerr case is anything to go by, something like black hole collision at a minimum.

Thanks for including links!  Now I have tonight's reading planned! 

 

And seeing as we believe that we are starting to detect black holes merging... https://www.nbcnews.com/science/space/biggest-bang-big-bang-scientists-detect-collision-huge-black-holes-rcna106

Do you know of anyone looking into the data for Kerr type catastrophes? 

Edited September 7, 2020 by JoeSchmuckatelli

[K^2]

3 hours ago, JoeSchmuckatelli said:

Do you know of anyone looking into the data for Kerr type catastrophes? 

It's unlikely to be exactly like Kerr naked singularity, because Kerr metric is very symmetric, and we don't know exactly what to look for. There are people trying to come up with plausible metrics that include CTC via computer modeling. I would expect anything interesting to come out of that first before we attempt to detect whether anything like it is happening.

Keep in mind that the way we are detecting events such as black hole merger is by comparing signals we get at gravity observatories to computer models. We don't really have a way to detect something new, other than getting a signal that doesn't match an existing model, at which point, the best we can do is shrug our shoulders and say, "We don't know what happened there, but it was energetic."

[kerbiloid]

Every time I meet a Kerr singularity, I recall that we may live in a closed timelike curve.

But then I wake up and still can't see any answer to the question about what is the time besides one of coordinate axes.

[ARS]

Very cool space fighter launching and recovery process from Space Battleship Yamato

Launching:

Recovery: