When I eat mustard (the hot English mustard, not the weak hotdog mustard), it always makes my nose run. So what's happening?

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Well cold air will constrict blood vessels which will reduce swelling a bit so that is part of it

That's a fun video. Thanks!

I've seen the fabric metaphor before, but I'm still having difficulty on not separating time and space from each other. I think now I'm very close to understanding though.

I'm starting to think that space is not really a volume, and it's more of a relative thing. Like if right now we could get rid of the half of the matter in space, like draw a line and cut it into two pieces like a pie, and simple erase one side, then the new center of the space would be the center of mass of the remaining half. Or let's say, if there was only one particle in the whole universe, then there would be no space since it couldn't move relative to anything. It couldn't have speed. So, space is not actually an empty volume, if there aren't more particles that can move relative to each other. What do you think? It's not correct, right? Is it?

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Yup, I'll just add that there's a lot of ways to clear other breathing issues beyond sinuses

Oxymetazoline is a general long-acting decongestant / vasoconstrictor for general sinuses or stuffy nose; fluticasone is a long acting mild glucocorticoid for allergies and mild asthma by opening up the brancioles in the lungs by reducing inflammation, as well puffers like salbutamol and ipratropium for short term asthma attacks and mildly low spo2 levels (+ used secondary for many issues beyond just asthma attacks)

The issue with methanol by itself is that, while it might alleviate the sensation, if your airway is significantly compromised its not going to do anything about low spo2 levels. But it's great for mild sinuses since it provides a bit of immediate relief. It's very often added to other decongestants that takes longer to start working for the same reason. Another alalogy is how people find it easier to breathe in colder air, especially during hot summer days

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Short answer is yes, but not enough to matter to a human. Tiny fractions of a second per year.

Interestingly though, it is enough to throw off GPS calculations which have to be VERY precise. GPS satellites have to include compensation for time dilation in their calculations or they wouldn't work.

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"Warm receptors will turn up their signal rate when they feel warmth—or heat transfer into the body. Cooling—or heat transfer out of the body—results in a decreased signal rate. Cold receptors, on the other hand, increase their firing rate during cooling and decrease it during warming" Yap two different receptors for different purposes... the more you learn :O

We have cold receptors? I thought we perceived cold as heat leaving our body ...

> But a person on ISS will tell you the same thing about earth!

You can only say that about spaceships flying past Earth in a straight line. The ISS goes in circles, i.e. always changes directions. Only the Earth reference frame is "inertial". As Duros001 said above, this creates not just a perceptual but an actual measurable difference between the clocks on Earth and ISS - the clock on ISS will tick slower and all observers will agree on that.

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It's not implying that with the measurable difference line, using measurable in that context is just taken to mean large or significant

If I have a completely blocked nose with no airflow, and get a smell or a mouthful of something strongly mint flavoured/smelling, my nostrils open and allow air to pass again. That's not just an illusion of cold air. Something has to be happening beyond a trick of the temperature sensing nerves.

It is, in the same way that light speed is the same for all observers. For example you travelling at the speed of light and turning on a flashlight results in the light emitted from the flash light moving forwards at lightspeed relative to you and we know that you can't go 2x the speed of light which is what would be happening from a 3rd perspective.

So the only way to reconcile this impossibility and maintain causality throughout the system, since nothing can go faster than light relative to any observer, is with time dilation.

Why does my nose start running when I melt actual menthol crystals and sniff the fumes then? Pretty sure those are the pure menthol, or near as dammit. They're definitely not laced with decongestants on purpose, because they're lab grade crystals meant for perfumeries.

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Gravity is the result of matter warping spacetime.

Imagine setting a really heavy bowling ball on a trampoline. It will sink, stretching and curving the fabric of the trampoline that otherwise was flat, uncurved. If you were to roll a smaller ball straight past (but not at) the well created by the bowling ball, it will circle the well, gradually spiraling inwards as it loses energy. Analagous to one body orbiting another.

Matter does pretty much the same thing to spacetime, but its in all directions (since spacetime isn't a flat plane like the trampline). Non-euclidean geometry is the geometry of curved surfaces (put simply) and can shed insight on some of your more specific questions.

Edit: watch this Video

The problem is our daily experience of how time and space operate is actually misleading. This makes it really unintuitive to conceptualise what's actually going on.

It turns out that time and space are the same thing which is called spacetime. Everything moves through this spacetime at the speed of light. There actually isn't any variation in speed of anything through spacetime. The only difference between anything is how much of their lightspeed through spacetime is specifically directed at moving through space and how much is directed at moving through time.

In order to move faster through space, you must deduct speed away from time because you have to maintain lightspeed through spacetime. This is also why you can't go faster than light. Firstly, you're already travelling at light speed through spacetime. Secondly, once you angle all of your light speed through spacetime so it's pointed at space then you have 0 angled at time and so you have no more speed to borrow from time to assign towards speed through space since you must always maintain lightspeed through spacetime.

In any given locality there are fundamental laws like not being able to travel faster than lightspeed and this also applies to the passing of time. It will always pass at one second per second for any local observer. Another law is that events between these different localities ultimately must be causally linked. The only way for events from one to impact the other and retain that causal relationship is if you introduce the concept of time dilation.

The one nit I have is with the very end. It implies that the time dilation at the ISS isn't measurable, but we do have precise-enough clocks to measure it, and have done so.

But overall, it's really impressive!

The experience of time is always the same for any local observer. Meaning that no matter where you are you will measure time passing at a rate of exactly one second per second. This means that it makes no sense to state that time is experienced differently because it is always experienced the same for any local observer and they're the only one who can have the experience of time at that specific locality. The only time there becomes a discrepancy is when time in one locality is measured relative to something else where there is a difference in either speed or gravity.

It's basically a measurement discrepancy rather than an experiential discrepancy.

Yeah I agree. People keep saying "it's just a trick!" but I've definitely been completely blocked and then been able to breathe after using menthol or something similar. You can even hear a click when it unblocks sometimes.

I've been meaning to try it ever since I heard this "it's a myth" thing on Reddit (seemed to start spreading within the last year) but I haven't had an actually blocked nose for ages.

I see, but that's weird.

In this sense, if this time-speed relation is continuous, the faster a thing will move, the less time flow it will experience. And as someone else suggested, if one could accelerate further, then it would have to see things going back, but that confuses me and it's another story, because me accelerating further would require me being observed as going backward too, but I'd be going the same direction... Then perhaps it's an automatic thing that, after this speed limit, the direction of the vector just rotates itself backwards? But that doesn't sound nice either.

I guess we will have to assume, speed of photon is the maximum, and zero is the minimum, and there can happen no bending beyond these extremes due to some dimensional restrictions or something.

Then, in a similar sense, something with zero speed, should experience the whole time being as fast as a moment, like the cosmos gets born and dies at the same time, yet it might have to stay still at the center of the universe for that, because its coordinates should never change to never have any speed, and at the beginning it was a point, I guess.