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[Max™]

Over in the direction of Vela about 49 Light Years away there's a low mass star with a ~1.6 Earth-Mass planet in a transiting orbit.

Recently observations were performed which showed a different radius in just a few wavelengths.

What does that mean?

https://www.keele.ac.uk/pressreleases/2017/atmospheredetectedaroundanearth-likeplanet.html

It's an atmosphere which we can study and so far best fit models suggest it is a steamy (600 K) methane-rich soup.

Not super exciting as far as finding life there goes, it remains possible that we'll find some, and honestly I would expect this to be the case. Just more like a gas-immersed version of deep sea vent colonies than a high tech civ I'd guess.

However it is critical because we weren't sure whether a low-mass star with planets near enough to be in the habitable zone could maintain an atmosphere over gigayears, but this one has!

[martinuzz]

Analyzing the data Cassini sent in 2015 of it's flyby of Saturn's moon Enceladus, scienctist have concluded that inside the small moon (only 500km across), there must be hydrothermal vents. With their article published in Science, all requirements seem to be met for the possibility of finding life in our own solar system.

Enceladus is a small moon, only 500km across, and is covered by a layer of frozen ice. Below the ice however, is a liquid ocean, kept warm by the tidal forces of Saturn pulling on it. In 2004, Cassini already discovered geyser like fountains erupting from the surface.

At October 28th 2015, Cassini flew straight through one of those fountains, at less than 50km above the moon's surface,and sent it's measurements back to earth.
These measurements show that the geysers contain hydrogen molecules.
According to US scientists, this can only be explained in one way: There are active geothermal vents at the coean's bottom. The hydrogen would be formed by hot water interacting with minerals in the soil.

Dutch bio-chemicists Jan de Leeuw, former director of the Royal Dutch Institute for Maritime Research says the discovery is "extraordinarily interesting".
Over the past years, it has become more and more clear that life on earth with near certainty must have evolved around such hydrothermal vents.
"Molecular hydrogen reacts with carbon dioxide, forming organic molecules like sugars, proteins and lipids, and eventually, RNA and DNA. That would be possible on Enceladus as well. What's special about it, is that life does not need light to evolve. The hydrothermal vents provide all the energy needed. On Enceladus, no light will penetrate the deep ocean".

To add some icing to the cake, Cassini also found traces of methane in the plumes. It's origin is yet unknown, but on earth, methane around hydrothermal vents is produced by micro-organisms.

Jupiter's moon Europa is similar, in that it has a liquid ocean beneath a frozen surface, kept warm by tidal forces. NASA has planned a mission in 2022. The Europa Clipper is either going to make a close flyby, or even attempt a soft landing there. Hopefully, NASA's next mission will be a landing on Enceladus. Perhaps they could even reroute and rename the Europa Clipper.

[wierd]

I disagree that hydrothermal vents are the only way to get elemental hydrogen molecules, in regard to Enceladus.

Remember, the E-ring is not just a gravitational feature!! (It is actually unstable!) It acts like a grounding or lightning rod with Saturn's magnetosphere, and is VERY VERY electrically charged!! More than enough current there to dissociate the water molecules in the hydrodynamic plumes erupting from the surface of Enceladus to account for a very strong elemental hydrogen signal.

Now, if they see some other exotic chemistry, such as involving sulfur, that would be very indicative of hydrothermal processes suitable for sustaining a biosphere.

(edited for correctness. Enceladus is in the E ring, not the D ring. Derp!)

[wierd]

https://www.astro.umd.edu/~dphamil/research/reprints/HorHamBurns92.pdf

http://www.sciencedirect.com/science/article/pii/S0019103516302408

http://onlinelibrary.wiley.com/doi/10.1029/2007RG000238/full

https://www.nasa.gov/multimedia/imagegallery/image_feature_2069.html

and others.

Basically, enceladus has a rather strong ring current passing through it, from the interaction of the plasma torus with saturn's magnetosphere. This excites the moon, giving tremendous energy that reinforce/cause the jets on the moon, which then expel conductive particles into the plasma torus, which then provide a grounding path and a co-rotating secondary plasma torus.

You don't get an atmospheric spike of OH, from H2O, without producing H2.

(edit, removed probably dubious holoscience link, replaced with more reputable nasa one.)

[wierd]

Devil is in the details then.  Like usual, the press botches the job, and says "All the hydrogen, totally from hydrothermal stuff! scientist says so!"

when what scientist really says is "There is an otherwise unaccounted for excess of elemental hydrogen in the plume, that is best explained by hydrothermal processes."

gotta love science reporting.

[Max™]

Plus the confusion of there being two different papers out which can both be described as a time crystal and which are totally different: the oscillating ion one where they keep cycling without needing to add energy (wrongly called perpetual motion too, it's almost the bad science reporting trifecta!) and the broken temporal symmetry one where the evolution of the system doesn't exhibit time translation symmetry... and I totally forgot where I was because I was trying to get the damn ceiling fan in the other room to speed back up, got WD40 on my forehead and beard, bleh.

[MetalSlimeHunt]

The presence of unaccounted-for methane is something I've heard before, regarding Mars instead of Enceladus. Interesting trend, but maybe we're missing some common source that has nothing to do with life.

[WillowLuman]

Hoo boy, I remember that "time crystal" debacle. Particularly because certain new age nuts I have contact with on social media heard the phrase "time crystal" in the news and just ran with it.

[JoshuaFH]

I've been a fan of astronomy for quite a while, and I've been watching stuff like PBS Spacetime on Youtube as something I'm vaguely interested in. Some of the stuff flies over my head, but I have a question if anyone has an answer: Is... is movement, and by extention all the space that that movement takes place in, an illusion? That's probably phrased stupidly, but I was thinking about relativity, like, that there is a speed limit that nothing can reach, and that's c, the speed of light. What defines movement though? What is an object's velocity being compared to which determines how 'fast' it is going compared to light? Relativity, if I'm understanding it correctly, is that light is always moving at c, no matter how fast *you* are going, from your perspective, due to time dilation. That because time slows down as you speed up, from your perspective light is always moving just as fast as it always is, you never perceive yourself as 'catching up' to it no matter how hard you're hitting the gas on your space ship, light is always just that much faster because we're measuring ourselves against it. But again, what is movement? I suppose it is the relative speed we perceive ourselves to be moving in relation to other objects. So, assuming that we can build two spaceships that can move at 50% c, and we have them do a full speed flyby past eachother, would each one see the other as moving *at* c, since their relative speeds are additive to their observations?

Though another thing I don't get about time dilation, is that since light is moving at c, time is not moving for the light photon at all. If a photon is created, and it travels 100,000,000 light years across the universe until it hits an object, then obviously a hundred million years passed from our perspective, but from the photon's perspective that entire journey happened instantaneously... How is that possible, how can something experience no time, but also be able to move? I feel that there is something really fundamental I'm missing here.

But getting back to the 'movement and space is an illusion' question, I take it that photons, and other fundamental particles that makes up atoms, are actually moving through a kinda of 'field' that gives them mass. That all the electrons and protons and crap are just whizzing about in this field, and that is what makes them 'real', that they're all *trying* to move at c, but this field slows them down and makes them live a humble life as part of a molecule or something, otherwise they'd all be... energy? This is the part I'm sketchiest on, the idea that energy is matter and matter is energy, just in different forms, but what I took away from it is that, reduced to their smallest particles, everything just wants to move at c, everything wants to exist in that timeless perspective, so to us in the macroscopic world, time and space are realities, but to the quantum world, the world which makes up all the atoms we are made of, time and space are illusions...

I actually wanted to ask this question to Neil Degrasse Tyson when he visited Detroit, which is within driving distance from me, but I just couldn't make it. Perhaps it's for the best, I probably would have embarrassed myself trying to spit it all out in front of him.

[Pwnzerfaust]

I suppose it is the relative speed we perceive ourselves to be moving in relation to other objects. So, assuming that we can build two spaceships that can move at 50% c, and we have them do a full speed flyby past eachother, would each one see the other as moving *at* c, since their relative speeds are additive to their observations?

Not quite, no. In special relativity, the (abbreviated) formula of addition of relative velocities can be expressed as v = (a + b)/(1 + (a*b)). So in this case we would take (0.5 + 0.5)/(1 + (0.5 * 0.5)) = 0.8. So having two ships pass at 0.5 c, due to time dilation their relative velocity is still only 0.8 c. Indeed even if they were each moving at 0.95 c in opposite directions, their relative velocities would only be 0.9986 c.

It's.... It's kind of fucky to wrap one's head around and very counter-intuitive.

Though another thing I don't get about time dilation, is that since light is moving at c, time is not moving for the light photon at all. If a photon is created, and it travels 100,000,000 light years across the universe until it hits an object, then obviously a hundred million years passed from our perspective, but from the photon's perspective that entire journey happened instantaneously... How is that possible, how can something experience no time, but also be able to move? I feel that there is something really fundamental I'm missing here.

Yes. No time passes for photons. From their point of view as it were, they were emitted from a start a dozen lightyears away the same instant they were absorbed by your eyeball. Again, very weird and counterintuitive.

[Il Palazzo]

snip

1. We're always measuring velocity against something else. This is not specific to special relativity - works the same in the more mundane, 'Galillean' relativity. I.e. there's no such thing as velocity without some reference point, in the same way as there's no distance without specifyinig what you're measuring it against.

2. Re: Two spaceships. With relativistic velocities you always need to specify what you're measuring them against as you change reference frames. In this case, the two ships are moving at 0.5 c w/r to some stationary observer in the middle. If you then change the reference frame to one of the ships, then each will see the other as moving at ~0.8c (you need to use the relativistic velocity addition formula). As for the observer in the middle - he can measure something called 'rapidity', which is the speed of separation between the ships that he observes. It is added normally (without relativistic corrections), and indeed adds up to 1 c. Similarly, rapidity of two opposite light beams is 2 c. However, note that nothing is actually moving, in the strict sense, with velocity equal to rapidity.
edit: no, wait. Having checked that's not rapidity. Separation velocity? I can't recall the nomenclature atm.

3. There's no such thing as time perceived by light. This is because in order to even talk about passage of time you need a stationary reference frame, and there's no such frame for light - it contradicts the postulate that light moves at c in all frames. You just can't have both.
You can observe velocities arbitrarily close to the speed of light, with associated arbitrarily dilated time. But for the speed of light itself time passage is undefined.

I'm not going to attempt the Higgs field and everything is illusion questions.

[Starver]

It's not an embarrassing question. Relativity issues are contrary to more mundane everyday experiences because the throwing of balls (for example) does not have significant relativistic effects to experience, and even supersonic flight (as dictated by the medium one travels in) isn't going to show any effects unless you carry a particularly accurate clock with you.

Firstly, "c" is not really the speed of light that nothing else can reach, it is actually the speed of causality that only things like light (or gravity) can reach.  Light can be slowed (or made to take longer/more contrived paths), but unfettered light does indeed go "the speed of light in a vacuum", relative to... Anything, indeed everything. That's the fundamental thing, but light is just the more obvious thing to try to measure.

...and, I've just to been asked to do something, which means I'm going to pause my own version of the explanation.  I'll get back to this in an hojr, maybe, unless someone else cares to take up the baton (maybe even correct any imprecise/misleading language, so far used...)

(Ah, two replies even whilst I was typing this. I'll have to read them later, too...)

[Il Palazzo]

No time passes for photons. From their point of view as it were

There's no such thing as their point of view, though. See above.

[Pwnzerfaust]

I said "as it were" because I couldn't think of a better way of framing it. My point still stands.

[Il Palazzo]

My point still stands.

How? It doesn't make sense otherwise.