JackDole wrote:

A thought while watching a video about quantum entanglement:
If quantum entanglements really exist, that is only possible in my opinion if space is not what we think.
If what we see as space is only an illusion, if what we see as distance does not exist in reality at all.

Thats correct.  I remember also reading that tachyonic particles are possible, but we cannot detect them.  Tachyonic matter is crucial to some well established theories, but they can't be used in any practical way.  As a matter of fact you could construct a model of the universe where causality itself is violated but it wouldn't make a difference to us because there is no way for us to detect such violations.  That makes me ponder if it's possible that all points in time also exist simultaneously so, in effect, the universe has already experienced heat death (or bounced back or whatever is going to happen to it.)

And the ironic thing about "patterns" is that you can even find patterns in randomness!

Is it possible to have planets with fresh water seas instead of salt water seas?.... And if so, how difficult would the circumstances be?

senuaafo wrote:

Source of the post Is it possible to have planets with fresh water seas instead of salt water seas?.... And if so, how difficult would the circumstances be?

To answer this, you must know why Earth's oceans are salty. The salt in ocean water is a mix of the minerals sodium, chloride, sulfate, magnesium, calcium, potassium, bicarbonate and bromide. These are nowadays washed into the oceans by rivers, whose sediment is rich with these compounds gathered from their meandering courses through the land, which liberated these salts from the rocks they flow over. Ancient ocean bedrocks can also release salt, because those rocks were often from ancient volcanoes, and their contact with the water dissolves these compounds in the surrounding water, making it acidic. The acids dissolved minerals from lava, producing ions. More recently, ions from eroded rocks entered the ocean as the rivers drained into the sea. When these salts are deposited into the ocean by the action of rivers or otherwise, they have no-where to go and thus either settle on the seafloor or float in the water.

Overall salt density in the water depends on the evaporation rate of the ocean. Evaporation can be roughly equaled to a number of factors all combined, such as the size of the ocean, its temperature, the amounts of salt deposited in it and so forth. All oceans since their early inception on our planet have maintained a balance of water evaporation/condensation and salt depositing with these factors. Most global oceans nowadays have around 35 parts per thousandth of salt in their waters. In some places, overall evaporation can be too great for whatever reason, and all the water can disappear and only the deposited salt remains, creating a salt flat. With lakes, the water evaporation is almost non-existent unless they are seasonal, and not enough minerals are present in the sediments to altogether give the water any great salinity. In some lakes, there can exist a perfect combination of minerals and temperature that the waters can be salty - often quite so.




So, it would not be very hard for an exoplanet with the right surface conditions for the maintenance of a atmospheric water cycle to have low-salinity or non-saline seas. It would just depend on the evaporation-rate of the water and the amount of sediments that are deposited in whichever body of water by rivers or other forces (like volcanism).  An example would be a planet orbiting a star with a lower metallicity then our sun, or maybe a planet whose surface consists of many, many shallow but large inland seas with little to no geological activity beneath them or much incoming sediments in their river deltas. That being all said, salt in the oceans may have played an important role in the development of life on Earth - so such less-salty worlds might well be barren, at least of life as we know it.

Thank you stellarator, that was a great answer. It seems that given the riches of minerals, ect, on a  theoretical habitable planet, fresh water oceans would be quite a reach, especially with a later generation star.... so I guess I'll stick with regular salty oceans and just use abundant rain/evap cycles and large fresh water lakes on the continents.

Found a planet in SE that has an atmosphere of 74% oxygen, 24% carbon dioxide, and nearly one percent methane. Would the whole atmosphere explode or something if I opened a lighter on the surface?

I mean, that just doesn't look sustainable to me.

Mouthwash wrote:

Source of the post  Would the whole atmosphere explode or something if I opened a lighter on the surface?

No.  For the atmosphere itself to ignite the oxygen-methane mixture needs to be sufficiently close to the stoichiometric 2:1 ratio.  The best way to see this is with a flammability diagram.  In this particular case, 1% methane and 74% oxygen is well outside the flammable range.

It would definitely make most materials more readily combustible, however, and it probably would not be a good idea for you to use your lighter as you might set yourself on fire.  But the air itself won't explode.

Mouthwash wrote:

Found a planet in SE that has an atmosphere of 74% oxygen, 24% carbon dioxide, and nearly one percent methane. Would the whole atmosphere explode or something if I opened a lighter on the surface?

I mean, that just doesn't look sustainable to me.

Whats the color of the sky in day time?

A-L-E-X wrote:

Mouthwash wrote:

Found a planet in SE that has an atmosphere of 74% oxygen, 24% carbon dioxide, and nearly one percent methane. Would the whole atmosphere explode or something if I opened a lighter on the surface?

I mean, that just doesn't look sustainable to me.

Whats the color of the sky in day time?

Basically the same as Earth's, despite being around a white main sequence star. Even has about the same atm.

Unless there was a significant presence of dust or aerosols in the air, a heady atmosphere of O₂ and CH₄ would be colorless and visibly indistinguishable from our "normal" air of O₂ and N₂.

When looking at a map of the universe, I see a bunch of strings throughout the image. What are they and why are they there?

PlutonianEmpire wrote:

Source of the post When looking at a map of the universe, I see a bunch of strings throughout the image. What are they and why are they there?

This is just the Laniakea supercluster of galaxies (Is the supercluster where the Milky Way is located and some 100.000 other galaxies). Important to note the difference between these structures and the large scale structure of the universe.
When you see images like this:

You are seen the large scale structure of the universe, with tens or hundreths of millions of galaxies. In that case, the filaments you are seeing are actual physical structures, bridges made of hundreds of galaxies connecting galactic superclusters (the nodes of the network). The foam-like appearence (made by filaments, voids and clusters) is a consequence of the behaviour of gravity at these huge scales when matter is spread very evenly across vast distances. We have seen these filaments form also in large simulations like this one:


The filaments shown in your picture of Laniakea is something different.
Those lines do not represent actual physical structures but are field lines. What field? The velocity field of each individual galaxy of this region under the gravitational potential in this particular portion of the universe. They were drawn for the Nature magazine cover for the discovery of Laniakea to show how we expect galaxies of our extended galactic neightbourhood to move in the next billion years. The red dot marks where the Milky way is located. Laniakea is basically defined as the galaxies that in a non expanding universe would collapse towards the so called Great Atractor (a region with overdensity of galaxies). The lines are almost the paths each galaxy of laniakea would take to get there (if the universe was not expanding). You can see in the bottom-right corner and top-left corner of your image that there are other lines, disconnected from the central system; those are neighbouring galactic superclusters, adyacent to Laniakea (a galaxy there is bound to another system of galaxies).
The best way to quickly grasp something about how cosmologists visualize these things is to watch this awesome video:


In the minute 11:45 they show how these field lines are generated.
Also, a video with identical visualization tools was made for the Laniakea discovery:


I probably said something wrong. But since Watsisname is a cosmologist maybe he can tell us more.

the large scale structure does look like the neuronic structure of the brain

FastFourierTransform wrote:

PlutonianEmpire wrote:

Source of the post When looking at a map of the universe, I see a bunch of strings throughout the image. What are they and why are they there?

This is just the Laniakea supercluster of galaxies (Is the supercluster where the Milky Way is located and some 100.000 other galaxies). Important to note the difference between these structures and the large scale structure of the universe.
When you see images like this:

You are seen the large scale structure of the universe, with tens or hundreths of millions of galaxies. In that case, the filaments you are seeing are actual physical structures, bridges made of hundreds of galaxies connecting galactic superclusters (the nodes of the network). The foam-like appearence (made by filaments, voids and clusters) is a consequence of the behaviour of gravity at these huge scales when matter is spread very evenly across vast distances. We have seen these filaments form also in large simulations like this one:


The filaments shown in your picture of Laniakea is something different.
Those lines do not represent actual physical structures but are field lines. What field? The velocity field of each individual galaxy of this region under the gravitational potential in this particular portion of the universe. They were drawn for the Nature magazine cover for the discovery of Laniakea to show how we expect galaxies of our extended galactic neightbourhood to move in the next billion years. The red dot marks where the Milky way is located. Laniakea is basically defined as the galaxies that in a non expanding universe would collapse towards the so called Great Atractor (a region with overdensity of galaxies). The lines are almost the paths each galaxy of laniakea would take to get there (if the universe was not expanding). You can see in the bottom-right corner and top-left corner of your image that there are other lines, disconnected from the central system; those are neighbouring galactic superclusters, adyacent to Laniakea (a galaxy there is bound to another system of galaxies).
The best way to quickly grasp something about how cosmologists visualize these things is to watch this awesome video:


In the minute 11:45 the start to show how this field lines generate.
Also, a video with identical visualization tools was made for the Laniakea discovery:

Exactly the answers I was looking for, thank you!

I probably said something wrong. But since Watsisname is a cosmologist maybe he can tell us more.

He ignored it when I posted this question on the SE discord, so I deleted it and reposted here and on reddit. Make of that what you will.

PlutonianEmpire wrote:

Source of the post He ignored it when I posted this question on the SE discord, so I deleted it and reposted here and on reddit.

   I can't ignore something that I never saw!  I'm not continuously on Discord, but when I log in I always check and reply to messages that were pinged at me.  Maybe you deleted it too soon?

At any rate, FFT's answer is very accurate and complete.   There isn't much to add.  On very large scales the universe is expanding, but localized regions (still quite large -- a few hundred million light years across) can be denser than average and the matter and galaxies in those regions break off from the expansion and collapse together by gravity, forming walls and sheets of superclusters like Laniakea.  Regions that are less dense than average empty out and become the voids.  The curving paths in the Laniakea graphics are a way to visualize how the galaxies in our supercluster are bound together and moving around in its own gravity well.

Fair enough, my apologies.

Ja that makes sense, thank you. Also, in FFT's first vid, could that also be how IC 1101's current appearance may have formed?