How would scientists try to explain this omen?

[The Great Wyrm]

In a campaign I'm designing, there will be an omen: a glowing sigil will appear in the sky, and seem to be directly overhead at all points on the globe.

How would physicists that don't believe in magic try to explain this? What would be their most parsimonious model?

(The light of Venus refracting off swamp gas from a weather balloon?)

[gomipile]

If it was as you describe, most honest physicists would say "I don't know."

If it truly appeared directly overhead everywhere, the simplest explanation wouldn't be very simple. I'm imagining the entire planet being surrounded with a spherical holographic image film. Or, perhaps the effect could come from a large number of close-to-perfectly collimated lasers in a sphere around the planet, all aimed at Earth's center.

[Ravens_cry]

As said above, am honest scientist would say 'I don't know'. They might hypothesize some non-magical explanations, but, magical or not, it is still clearly the work of intelligence, though human or not is another question, though the scale suggests non-human.
The 'scientist in denial' trope is rather overdone in my opinion. Rationality isn't some dogma, or at least it shouldn't be, and you can do science to magical effects more often than one might think.

[Cespenar]

When in doubt, use nth dimension shenanigans.

Or, it could be a planet-spanning mind effect.

Why would physicists not "believe" in "magic" anyway? The "Any sufficiently advanced technology is indistinguishable from magic." quote isn't famous for nothing.

They'd likely be trying experiments, observing the sigil from outside the atmosphere, through cameras, various telescopes, etc. before coming up with any hypotheses.

[Jomo]

Of course some people who are trying to be rational would come up with explanations and stubbornly stick to them. They just wouldn't be thinking scientifically.

[factotum]

A sigil which somehow appears directly overhead for *everyone* can't possibly be an external phenomenon--it would have to be implanted in the minds or eyeballs of the people watching.

[HandofShadows]

A sigil which somehow appears directly overhead for *everyone* can't possibly be an external phenomenon--it would have to be implanted in the minds or eyeballs of the people watching.

Sounds like a memetic hazard (http://www.scp-wiki.net/understanding-memetics) from the SCP Foundationverse. Memetics are things that "hack" the human brain and make you think belive things just by seeing them. Or seeing a picture of them, or even reading a report about them. Heck even knowing the meme even EXISTS is enough to be infected by it.

Here's a well known example for one known as The Final Countdown (http://www.scp-wiki.net/scp-902).

What's in the box must be destroyed. Right now. Before the countdown ends. We have to destroy it. Now. I know the box is empty, but we still have to destroy what's inside of it. Before the counddown ends it must be destroyed.

[Devils_Advocate]

Sounds blatantly artificial. Presumably somehow produced by unknown technology.


A sigil which somehow appears directly overhead for *everyone* can't possibly be an external phenomenon
Does that follow from some known principle? I don't know enough about optics and whatnot to say.


it would have to be implanted in the minds or eyeballs of the people watching.
My first thought is nanotech, but there's always the "We're all living in a simulation" angle.

[Kato]

A sigil which somehow appears directly overhead for *everyone* can't possibly be an external phenomenon--it would have to be implanted in the minds or eyeballs of the people watching.

This. If two people are say 100km apart, it can't be directly above them, or if it's two sigils, both should be able to see both. It must be a mind effect or such.

Granted, there is no good scientific basis for that either but mass hallucination seems like what I would go for. Reasoning... uhm.. drugged drinking water? No idea.

[The Great Wyrm]

I think the explanations of "advanced alien technology" and "we're living in a simulation" are the likely ones for most scientists to give. Of course, I would expect them to intensely study the phenomenon.

I know the trope of "scientist in denial" is overused, so I won't make it seem like the scientists are stupid.

[NichG]

It can be directly above everyone if using the holographic film/collimated laser trick mentioned upthread. It's not a day to day situation (we're used to light scattering off of surfaces every which-way in daily experience, but it doesn't have to be like that).

That said, the first thing to do rather than to debate mental effect versus holographic film is to make really simple measurements. Stick a camera on the ground pointed up and use angled slats to see if A) the camera can see it at all and B) the light is coming in parallel. Measure for speckle to see if the light is coherent. Measure spectra. Try vertical variation in the view point.

If only people can see it, does it respect occlusion (e.g. can it be seen through obstacles)? Does this involve a transfer of information to observers that they would not be able to possess on their own (e.g. can you change the occlusion without them being able to see you do it, and they detect that the symbol appears/disappears)? What if you rotate the person in such a way that they aren't aware - do they have a perfect compass now?

Basically, characterize the physical phenomenon objectively; if there's nothing objectively measurable, use information transfer as a test to constrain the properties of the subjective experience.

[Kato]

It can be directly above everyone if using the holographic film/collimated laser trick mentioned upthread. It's not a day to day situation (we're used to light scattering off of surfaces every which-way in daily experience, but it doesn't have to be like that).


You mean a number of satellites sufficient to shoot a laser in every persons eye perfectly to create that illusion? I'm way more willing to believe in mass hypnotism that that. Heck, even if we had made contact with aliens :smalltongue:


While your analysis is of course smart, I was assuming the sigil to be only temporary, so no time for this. Though OP never said so, so I guess it was my interpretation of an omen in the way of reading it.

[WhatThePhysics]

In a campaign I'm designing, there will be an omen: a glowing sigil will appear in the sky, and seem to be directly overhead at all points on the globe.

How would physicists that don't believe in magic try to explain this? What would be their most parsimonious model?

(The light of Venus refracting off swamp gas from a weather balloon?)

If the sigil was not detected by cameras/satellites, only existed in the minds of humans that could see it, and everyone that was conscious at the time observed it overhead relative to their location, then scientists in denial of magic's existence could claim it's proof that deities exist.

If you really wanted to stretch the limits of scientific possibilities, one way to make such an event happen is to spread invasive nanomachines that simultaneously trigger a specific hallucination in every human mind. If humans lack such capacities in the setting, aliens could be a viable source. Once the brain scans and blood tests turn up negative for psychoactive nanomachines, they could argue that the stuff was designed to dissolve after the timed global hallucination.

That, or it's proof that reality is a simulation, as stated earlier by other posters.

[The Great Wyrm]

For added strangeness: This sigil would show up on cameras, but it would appear to be a slightly different shape.

[The_Snark]

Here's a well known example for one known as The Final Countdown (http://www.scp-wiki.net/scp-902).

... okay, before clicking that link I was sure it'd go here (https://www.youtube.com/watch?v=9jK-NcRmVcw).

In my defense, I'm pretty sure mine is better-known, and that opening is awfully catchy. :smalltongue:

[NichG]

You mean a number of satellites sufficient to shoot a laser in every persons eye perfectly to create that illusion? I'm way more willing to believe in mass hypnotism that that. Heck, even if we had made contact with aliens :smalltongue:

You don't need individual satellites to do something like this. A big dust cloud with particles that align to Earth's magnetic field could do it too. There are natural holograms like this - on cold days, ice crystals tend to align with the vertical and create 'sun dogs' at specific points in the sky relative to the view angle of the viewer to the sun. Rainbows are also like this.

But this is the problem of jumping to extensive conclusions about mechanism before characterizing the phenomenon. There's almost always a lot of ways for any particular single piece of evidence to arise, so generally if you pick the first idea that fits and go with it it will usually be wrong.

Edit:

Since it appears on cameras... Does the shape vary over spectral bands? How about depending on the material or IOR of the lens array used to focus it? Does the presence of an electric or magnetic field around the lens array alter the shape?

[tantric]

while i was a grad student in (mathematical) ecology and epidemiology, i had a vision - of the god who is my avatar, dreaming jaguar. in addition to curing me of an addiction, he offered this advice: tomorrow you will be tempted to rationalize this experience. but there is a difference between rationalizing something and explaining it. rationalizing is what you do when you can't face 'i don't know, i don't understand'. it's not science. just because you can rationalize anything doesn't mean irrational things don't happen.

[Devils_Advocate]

Well, sure. People do irrational stuff all the time.

[obryn]

A good scientist would take a look at it, confess they have no idea how it works, and then go on to try and find out how it works.

[Leewei]

For added strangeness: This sigil would show up on cameras, but it would appear to be a slightly different shape.

I suppose the first thing scientists would do is to model the phenomenon. Get image data from as many points on our world as possible, including different altitudes. See if there is any predictability to the sigil's appearance. See if it is visible from outside of our atmosphere. Measure the light it produces. See if it can be affected by known physical interactions. Does it vary by brightness / presence of the sun? Can you fly a drone into it? What does it look like from the Hubble?

Depending on these answers, scientists would come up with theories about the sigils. Given the apparent symbolism, some intelligent agency is almost certainly producing them. Who or what it is, and why they're doing this, is something that is pretty wide open for interpretation.

[Lord Torath]

I suppose the first thing scientists would do is to model the phenomenon. Get image data from as many points on our world as possible, including different altitudes. See if there is any predictability to the sigil's appearance. See if it is visible from outside of our atmosphere. Measure the light it produces. See if it can be affected by known physical interactions. Does it vary by brightness / presence of the sun? Can you fly a drone into it? What does it look like from the Hubble?

Depending on these answers, scientists would come up with theories about the sigils. Given the apparent symbolism, some intelligent agency is almost certainly producing them. Who or what it is, and why they're doing this, is something that is pretty wide open for interpretation.This, except they'd never use Hubble. There is a vast array of earth-observing satellites they could use that would all work better, and Hubble would likely take two weeks to turn to focus on the phenomenon, as well as not being particularly suited for observing the Earth. The Discovr (http://epic.gsfc.nasa.gov/) satellite would be great, though!

[Leewei]

This, except they'd never use Hubble. There is a vast array of earth-observing satellites they could use that would all work better, and Hubble would likely take two weeks to turn to focus on the phenomenon, as well as not being particularly suited for observing the Earth. The Discovr (http://epic.gsfc.nasa.gov/) satellite would be great, though!

Note that the sigil is straight up from the viewer. An altitude isn't given. It'd make sense for the sigil to be within our atmosphere, but we'd need to determine this experimentally.

[gomipile]

Note that the sigil is straight up from the viewer. An altitude isn't given. It'd make sense for the sigil to be within our atmosphere, but we'd need to determine this experimentally.

If it is literally always straight above the viewer parallax cannot be measured, by definition. Therefore there is no reason to expect the distance(height) to be measurable or meaningful. What I'm saying, is that there's no reason for it to make sense that it would be within our atmosphere, based on the OP's given facts.

Taken to an extreme, the sigil appears to be directly above each of our eyes, individually. Thus, it would have the appearance of being an undefined distance away (due to the curvature of the Earth causing all rays "to" the sigil to diverge) based on any parallax measurement.

[pendell]

I agree with other posters that the first response would be 'insufficient data', followed by examination and observation.

However, just because it looks like a sigil doesn't mean they'd accept it as one right away. Apophenia (https://en.wikipedia.org/wiki/Apophenia) is a thing. People who can see constellations in star patterns or faces on moon or religious figure's faces in pancakes might also assign meaning to a purely random pattern.

Barring some kind of communication with the creating intelligence, I suspect there could very easily be a division among scientists; some believing it to be a work of extraterrestrial intelligence, others believing it is a purely natural phenomenon which bears only a coincidental resemblance to human writing or symbols.

I suspect also that the hypothesis 'this is the creation of intelligence' would be accepted only when natural hypotheses have been ruled out. I say this because humans have assigned any number of natural phenomena in the past to the action of intelligent beings, when things like disease et al later proved to be the result of, say, bacteria rather than demons or evil spirits.

So I think most scientists wouldn't know what to make of it; but they would not leap to the conclusion that it was the creation of intelligence absent supporting evidence; they don't know they're living in a fictional world, after all :smallamused:

Respectfully,

Brian P.

[Excession]

If it is literally always straight above the viewer parallax cannot be measured, by definition. Therefore there is no reason to expect the distance(height) to be measurable or meaningful. What I'm saying, is that there's no reason for it to make sense that it would be within our atmosphere, based on the OP's given facts.

If you make an assumption about the base spectra, you could work out how much atmosphere the light had passed through. Measurements from multiple altitudes would help improve your model of the base spectra. Simply flying up until it disappears might work too. If that shows it's coming from space, you next step is to position yourself so the moon is straight up, and see if that occludes it. Repeat with the sun and planets for longer distances, then stars, galactic dust clouds, and even other galaxies as required.

If it's short lived, you won't have enough data. But even if there's only enough time for someone to point a telescope to straight up you might get all sorts of stuff.

There would be a frenzy of testing going on, assuming the phenomenon stuck around long enough for it. Many scientists would be saying "I don't know yet" or "I'm busy, ask someone else". Of course, a "scientist" on the TV news might just be a crack-pot with a PhD, so you could get all sorts of weird theories presented as facts. Many people will be desperate for answers, so will latch on to all sorts of silly ideas.

[Absol197]

If you make an assumption about the base spectra, you could work out how much atmosphere the light had passed through. Measurements from multiple altitudes would help improve your model of the base spectra. Simply flying up until it disappears might work too. If that shows it's coming from space, you next step is to position yourself so the moon is straight up, and see if that occludes it. Repeat with the sun and planets for longer distances, then stars, galactic dust clouds, and even other galaxies as required.

And then they notice that any object OUTSIDE our solar system occludes it, and anything INSIDE our solar system doesn't, and they are supremely confused :smalltongue: .

[gomipile]

And then they notice that any object OUTSIDE our solar system occludes it, and anything INSIDE our solar system doesn't, and they are supremely confused :smalltongue: .

If I noticed that while documenting and observing this phenomenon, I'd probably sigh, look up at the sky, and say "Now you're just being silly."

[Jay R]

"This phenomenon is as not yet fully understood, and does not follow known laws of physics. Therefore it represents a unique opportunity to learn new physical laws. Enclosed please find a two million dollar grant proposal to study the causes and implications of this phenomenon."

[Lord Torath]

Note that the sigil is straight up from the viewer. An altitude isn't given. It'd make sense for the sigil to be within our atmosphere, but we'd need to determine this experimentally.What is "Straight Up" for a satellite? For something near Earth, it could be directly away from Earth's center of mass. But for something farther away, what counts as "up"? Could Cassini see it (http://www.slate.com/blogs/bad_astronomy/2013/07/23/earth_from_afar_cassini_and_messenger_spacecraft_p hotos_of_our_planet.html), looking back from Saturn's Orbit? What counts as "up" for Cassini?
If I noticed that while documenting and observing this phenomenon, I'd probably sigh, look up at the sky, and say "Now you're just being silly.":smallbiggrin:

[NichG]

If I noticed that while documenting and observing this phenomenon, I'd probably sigh, look up at the sky, and say "Now you're just being silly."

I think you could get something that effect if you were viewing something from inside an optical element which is focusing incoming light to form the image. In that case, the image will be constructed from convergent light from many directions within the optical element (hard to occlude), but outside the optical element the light rays would be (more) parallel and would be consistently occluded by a single object. Think of how a small mark on a glass pane occludes your vision less when the pane is close to your eyes than when it's far away (it's not exactly analogous, since there the rays aren't parallel on either side and there's a finite focal distance, but to get an idea how a nearby thing can occlude less than a far away one).

[Ruslan]

A sigil which somehow appears directly overhead for *everyone* can't possibly be an external phenomenon--it would have to be implanted in the minds or eyeballs of the people watching.
I wonder what happens if you take a photograph of the sky then.

[keybounce]

So, different people see this thing in the sky in different places, and no two people are in agreement as to where it is?

That sounds like a rainbow. So maybe something similar is going on?

[Leewei]

What is "Straight Up" for a satellite? For something near Earth, it could be directly away from Earth's center of mass. But for something farther away, what counts as "up"? Could Cassini see it (http://www.slate.com/blogs/bad_astronomy/2013/07/23/earth_from_afar_cassini_and_messenger_spacecraft_p hotos_of_our_planet.html), looking back from Saturn's Orbit? What counts as "up" for Cassini?
Pretty much my point as well. We'd want to determine how orientation and location worked with the sigil. "Straight up" doesn't cut it once you go up beyond some point.

Back to the OP, I'm thinking a lot of the scientific community would view this phenomenon as strong evidence that we were living in a simulation.

[russdm]

Back to the OP, I'm thinking a lot of the scientific community would view this phenomenon as strong evidence that we were living in a simulation.

Doesn't figuring this out require some kind of evidence that can't be simulated, making any attempt to prove it impossible? "Are we living in a simulation?" is apparently turning into something big, because I don't think science is capable of proving this or disproving this because:

If we are in a simulation, then the simulation will be rigged to teach us about science, meaning that if we are in a simulation then all of our science is simulated. If we are not living in a simulation, then none of our science is simulation is simulated. Those ideas are mutually exclusive, because simulated science can not be real.

What why can you determine that since wouldn't any test of a simulated system within the system not work?

[gomipile]

Doesn't figuring this out require some kind of evidence that can't be simulated, making any attempt to prove it impossible? "Are we living in a simulation?" is apparently turning into something big, because I don't think science is capable of proving this or disproving this because:

If we are in a simulation, then the simulation will be rigged to teach us about science, meaning that if we are in a simulation then all of our science is simulated. If we are not living in a simulation, then none of our science is simulation is simulated. Those ideas are mutually exclusive, because simulated science can not be real.

What why can you determine that since wouldn't any test of a simulated system within the system not work?

The only way to prove it is if the controller of the simulation started messing with it from the outside in a way we could reliably observe.

Which, I think, is related to Leewei's point.

[NichG]

Doesn't figuring this out require some kind of evidence that can't be simulated, making any attempt to prove it impossible? "Are we living in a simulation?" is apparently turning into something big, because I don't think science is capable of proving this or disproving this because:

If we are in a simulation, then the simulation will be rigged to teach us about science, meaning that if we are in a simulation then all of our science is simulated. If we are not living in a simulation, then none of our science is simulation is simulated. Those ideas are mutually exclusive, because simulated science can not be real.

What why can you determine that since wouldn't any test of a simulated system within the system not work?

Well, mostly I'd say serious scientists don't believe this. It can be a useful thought experiment because it does force you to ask 'what is universal' versus 'what could be a parameter' (for example, could you make a simulation in which all embedded ways of calculating pi returned a consistently different result?). In turn, its the kind of question that helps you be critical about p-value types of reasoning (e.g. 'lets propose a model and a null hypothesis, and see which is better' isn't so impressive when you realize that there can be multiple models that give identical results).

So in turn there should be ways to test it. Most simulations we've made with digital computing infrastructure would have some common features, such as discretization errors and roundoff errors. Large-scale simulations will tend to also use aggressive approximation schemes (because the point of making it large-scale is usually to push the bounds of simulation into some new regime to obtain new results, not just re-simulate stuff we've been able to do before, so everyone tries everything at their disposal to make things more efficient). You could go hunting for the signature of those things, though it'd be hard to call any of them definitive proof of anything (you might however be able to demonstrate things like 'space and time are quantized at such a scale, computing the dynamics of the universe is an O(N^3) problem, ...'). Of course you can't say anything about alternative computational schemes either.

So talking about 'evidence for the universe being a simulation' is hyperbolic. I wouldn't rush to take it seriously, especially not based on 'well, something happened I can't easily explain in 30 seconds of armchair physics, we must be living in a simulation and everything is arbitrary!'. Taking that as a causal explanation based on evidence is a last resort like 'it was a fluke', 'highly unlikely chance thermal fluctuation', 'I'm currently dreaming', etc.

[BeerMug Paladin]

"Ooooohhh! Something I don't understand! Let's stare at it!"

You can't make a model of something you have no data about. Step 1 of the scientific method is to gather data. We have a lot of different tools for gathering data. Even if it was a short duration phenomenon, there would likely still be a lot of data to gather.

Assuming it was a short duration phenomenon, there would likely arise many competing models. In that case, an experimental situation might not be able to discern which competing model is more accurate; it's unlikely that there would be much scientific consensus. That is, unique events can't be scienced-at. So any debate over which model fits best would be entirely speculative.

"Living in a simulation." isn't likely to be asserted. "A wizard did it." is more likely. "Thor is having stomach cramps." is even more likely. All three are equivalent explanations, with no way to differentiate between them experimentally. Science isn't about rationalizing data. Science is about demonstrating how the data you have came about. When you can't provide that demonstration, the proper response is, "I don't know."

Of course, this would be the scientific community's response as a whole. Individual scientists could introduce known human errors in their thinking process. In that case, the sky's the limit.

[Bohandas]

Most likely causes in approximately descending order from most to least plausible:
*Mass hysteria/folie a plusieurs
*Mass psychosis/insanity or mass exposure to psychoactive chemicals
(the 2 above are easy enough to prove or disprove; can they be photographed? Can these photographs be distinguished from photos taken of the same patch of sky before the phenomenon by a person who doesn't know beforehand which is which)
*Hoax or publicity stunt
(It would initially be assumed to be one of the first three options above, but ones similar to the next three below are may be considered if the first three are conclusively disproved)
*similar to 'hoax'/'publicity stunt' above but by some country's intelligence agency trolling for some reason.
*lots and lots of unlicensed fireworks/laserlight/rock-show-type-stage-effect displays
*Multiple supernovas (if it is sufficiently amorphous) or other phenomena that create bright lights in the sky
(the next few are grasping at straws but may be considered if all explanations consistent with what is normal fail. There is an extreme drop in likelihood between each of these last few)
*Extreme warping of spacetime (something in the black hole/wormhole/ white hole/ topological defect family but likely more complex) could potentially result in movement in any direction leading to the same place (though I've little idea what the specifics of this situation would be, and it would likely lead to the stars disappearing from the sky as well) but it wouldn;t explain the rune
*aliens
*metastability event
*godlike aliens á la the Cthulhu mythos, Scientology, 2001 A Space Odyssey, Star Trek Voyager, and the Church of the SubGenius
*Ragnarok/the apocalypse/kali yuga/x-day/splice of eternity

[The_Ditto]

[crackpot posing as scientist]
This is continuing and indisputable evidence that we are living within a Hollow world!!
[/crackpot posing as scientist]
:smalltongue:

[keybounce]

Doesn't figuring this out require some kind of evidence that can't be simulated, making any attempt to prove it impossible? "Are we living in a simulation?" is apparently turning into something big, because I don't think science is capable of proving this or disproving this because:

If we are in a simulation, then the simulation will be rigged to teach us about science, meaning that if we are in a simulation then all of our science is simulated. If we are not living in a simulation, then none of our science is simulation is simulated. Those ideas are mutually exclusive, because simulated science can not be real.

What why can you determine that since wouldn't any test of a simulated system within the system not work?

Well, it's entirely possible that real physics does not follow the laws of math, and only this "fake physics" inside the matrix is the math-following foolishness.

But lets start with the hypothesis "we are in a simulation that is trying to be realistic".

For starters, as far as we know, any attempt to run a simulation has to be able to say "Here is the location of particle X", with some location system. If we can find that objects are either at this location, or that neighboring location, *and never anywhere in-between*, that's a really good indication that this is a simulation.

But that's going to be hard (at least close to plank-scale measurements). And, consider what if the simulation was done by plank-scale position? Well, then you have a grid-effect. No matter how you place an object, the next place you can move it to will be different distances based on the angle of travel. For a 3d square, that's 1, 1.414, or 1.7xx. Different "grids" will give you different errors, but all give you something. And that's in theory detectable.

Now consider what happens to high speed / high energy particles. G.R. says that our measurements of that high-speed stuff will not match our measurements of low-speed stuff, and even tells us what the difference will be. Yet any simulation has to have some "reference frame" -- so the behavior of different energy particles has some point where the simulation can't return the right result. And that's before taking the whole "frame warping" stuff into account that I don't know the math to understand.

The bottom line? The behavior near a black hole is not likely to be accurate. And suddenly, Ligo gives us our first set of measurements from such a situation.

What happens if we collect more Ligo events, and then discover that the data is not quite consistent with G.R.?

[Lord Torath]

What happens if we collect more Ligo events, and then discover that the data is not quite consistent with G.R.?Physicists everywhere will gleefully run to their whiteboards/computers to figure out a new law of gravity to replace it! Because that's what physicists (and really all scientists) love: a result that defies the current explanation.

[Kato]

Physicists everywhere will gleefully run to their whiteboards/computers to figure out a new law of gravity to replace it! Because that's what physicists (and really all scientists) love: a result that defies the current explanation.

After triple checking the equipment for errors and measurement uncertainty. Because, let's be honest, most things are due to one of these.
Don't get me wrong, I'd love to see a breakthrough in physics but I'm sceptical.

[HandofShadows]

Physicists everywhere will gleefully run to their whiteboards/computers to figure out a new law of gravity to replace it! Because that's what physicists (and really all scientists) love: a result that defies the current explanation.

I think this is the most realistic answer. Something new and defies all explanation? Real scientists love this to death because it's the chance to learn more.

[Leewei]

The only way to prove it is if the controller of the simulation started messing with it from the outside in a way we could reliably observe.

Which, I think, is related to Leewei's point.

Pretty much exactly my point, in fact. :smallsmile: