How many supernova explode every year?

Posted by rbanffy 4/12/2025

How many supernova explode every year?(badastronomy.beehiiv.com)

369 points | 187 commentspage 2

drbig 4/15/2025|

The universe is vast and full of nothing...

Which in case of explodey stars is a very good thing indeed!

layer8 4/15/2025||

It’s full of radiation everywhere, regardless in which direction we look and how highly we resolve it.

Iwan-Zotow 4/18/2025||

and neutrinos, there ought to be CNB

subscribed 4/15/2025||

It's fun to think that at some point it will be actually vast and completely dark

huxley 4/15/2025|||

One of the best infinitive canvas webcomics ever was done on that topic by Drew Weing: https://www.drewweing.com/puppages/13pup.html

jvm___ 4/15/2025||||

https://youtu.be/uD4izuDMUQA?si=LcVxE3w-ohGqZAr7

If you need some existential dread. It's a hypothetical video to portray the rest of the universe, the time speed moving forward doubles every 5 seconds - and it's 29 minutes long...

Obscurity4340 4/15/2025||

Really incredible video, thanks a quadrillion

rbanffy 4/15/2025|||

We have a couple trillion years to figure out a way to fix that.

loloquwowndueo 4/15/2025|||

We don’t need to fix that, do we? Just let it be. You’ll be long dead anyway.

h4ck_th3_pl4n3t 4/15/2025||

> We don’t need to fix that, do we? Just let it be. You’ll be long dead anyway.

Spotted the republican

loloquwowndueo 4/15/2025|||

Who, the guy I replied to who expects to be around in a trillion years and wants to live forever? Yeah, peak republican right there.

selectnull 4/15/2025|||

I guess even a republican can be right?

h4ck_th3_pl4n3t 4/15/2025||

/dev/random is right sometimes, too.

selectnull 4/15/2025||

If you ask someone "What is 2+2?" and they answer 4, you can say they are "right" even if you do not agree with them on other topics or generally dislike them.

If you ask /dev/random "What is 2+2?", that question makes no sense as /dev/random does not listen to you and just spits out random binary output.

Go and disagree with /dev/random.

h4ck_th3_pl4n3t 4/17/2025||

My point that you successfully explained and intentionally ignored is also: /dev/random ignores all state and evidence, meaning it will continue its predefined behavior even when it's damaging to the environment.

Pretty similar to a republican's mindset: I don't have to fix it, let the next generation deal with the problems that I caused.

selectnull 4/17/2025||

/dev/random is damaging to the environment???

Wobbles42 4/15/2025||||

Or to acquire the wisdom to accept it. We certainly are far too young to have a perspective to say which course of action is better -- or indeed to define what "better" means.

frainfreeze 4/15/2025|||

Does it need fixing?

rbanffy 4/15/2025||

Since I'd like to live forever, then yes.

db48x 4/15/2025|||

What you really want to do is put out the stars sooner then, and feed all the hydrogen into the supermassive black hole at the center of the galaxy. Dump in all the mass in the galaxy and all of its satellites and everything from Andromeda and its satellites too and it will grow. Nudge Andromeda’s central black hole into orbit around ours so that they merge, etc, etc. Grow it big enough and and you can build a Birch World around it, with a surface area larger than all the planets in those galaxies put together. All of the exploration with none of the boring travel in between interesting places! You can seed it with life from every planet your civilization ever encountered and watch all those ecosystems compete and hybridize as you while away the years. How many years would you have?

While dumping matter into a black hole destroys the matter, it doesn’t destroy the mass. It just confines all of the mass in one place. Powering your Birch World is just a matter of using the Penrose process to extract energy from the black hole for the next few million trillion trillion trillion trillion trillion trillion trillion years (about 3×10¹⁰⁴ years give or take a few). The stars will only last for about a million trillion years (10²⁰ years plus or minus a bit), so this plan extends your your lifetime by a factor of a trillion trillion trillion trillion trillion trillion years.

Maximal extension perhaps, but not quite forever. Forever takes a lot more work.

mietek 4/15/2025||

I would like to hear what you have to say about forever.

lazide 4/15/2025||

I imagine step 1 will be figuring out a way to reverse entropy?

db48x 4/15/2025|||

That’s actually [the _last_ question](https://users.ece.cmu.edu/~gamvrosi/thelastq.html), not the first.

I liked the DS9 episode where the mutants realized that the universe was collapsing into the Big Crunch, so they demanded “antigravity generators, lots of them!” Their cosmology was wrong, but only because the show had the misfortune to be written in the past. Their enthusiasm was great :)

rbanffy 4/15/2025|||

Something about there being light, IIRC.

8fingerlouie 4/15/2025||||

Technically you can live forever in a universe that is completely empty, it'll just be a lot of cold dark nothing for eternity.

Living forever is such a strange desire, considering that complex life has existed on earth for just a fraction of the time it has existed, and humanity even less than that. I recommend watching the Kurtzgesagt video called All of History in one hour (https://www.youtube.com/watch?v=S7TUe5w6RHo&t=3670s). It displays all of earths history in one hour, and humanity is merely a few seconds of it.

Earth is ~4.5 billion years old, that's 4500000000 years, and in 1300000000 years it will be uninhabitable by humans, and in another 4.5 billion years (roughly 3.2 billion years after becoming uninhabitable) it will be engulfed by the sun.

Assuming humanity manages interstellar space flight you could possibly escape earth and live somewhere else until that also dies, but in case it is not practical or possible, you get to enjoy 3.2 billion years of literally choking and being burned alive on earth.

Assuming you did escape earth (or you're immortal so escaping doesn't matter) In 1000000000000 years the last star will be born, and in 100000000000000 years the last star will die out.

You now have an extremely long time to enjoy suffocating in hard vacuum with your body being boiled by the low pressure, and all in complete darkness until the heat death of the universe occurs in roughly 10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 years

the_af 4/15/2025||

The Cosmos (both Sagan and Tyson's) shows also display the tiny fraction of life in the history of the universe with their "Cosmic Calendar".

Wobbles42 4/15/2025||||

I have to imagine that very few people would make statements like this if we lived in a universe where there was any real danger of it happening. It would be interesting to talk to humans that have lived even a few hundred subjective years, if any existed. That seems to be enough time to lead to very different perspectives on something like immortality. Given the information storage constraints of our minds, I wonder if there is even some age that makes immortality subjectively different than very long life. We don't seem to be capable of remembering even a full decade of experience. By the time you reach a few hundred years of age, would you have any memories at all of your first century? You might not have experienced a single "death" event, but the "you" that was born may have long since died.

pixl97 4/15/2025||||

>Since I'd like to live forever, then yes.

Please read this article first before damning yourself to an unimaginable hell.

https://waitbutwhy.com/2014/11/1000000-grahams-number.html

amelius 4/15/2025||||

Are you sure? At some point you have heard every possible joke that can be told in a timeframe of 10 minutes, 1000 times.

Wobbles42 4/15/2025||

It's very unlikely that I am capable of remembering every single joke that can be told in a timeframe of 10 minutes. If you were to take every such joke in a random order and put that on a loop, the experience would likely be one of perpetual novelty, even if you repeated it 1000 times.

amelius 4/15/2025|||

How about: every day there is a small but finite probability that you fall into a deep pit, and it may take years before people find you.

fc417fc802 4/16/2025|||

So you're saying that eventually Netflix can stop investing in new content?

6LLvveMx2koXfwn 4/15/2025|||

man, I couldn't think of anything worse - except maybe dynamic types

selectnull 4/15/2025||

Astronomers will find out that naming is hard once they need to name 119741st supernova.

pelagicAustral 4/15/2025|

I think it will be far before that, once they start hitting supernovae name jackpots like SN2026 cu*t et al.

selectnull 4/15/2025|||

I know :) This one was just the first to came to mind.

darthrupert 4/12/2025||

The whole things seems like such a massive living system that I cannot help guessing that what we think of as universe is just a somewhat large single creature.

Cyphase 4/15/2025||

This reminds me of this quote from Jill Tarter of SETI, specifically the last sentence:

“Might it be the discovery of a distant civilization and our common cosmic origins that finally drives home the message of the bond among all humans? Whether we’re born in San Francisco or Sudan or close to the heart of the Milky Way Galaxy, we are the products of a billion-year lineage of wandering stardust. We, all of us, are what happens when a primordial mixture of hydrogen and helium evolves for so long that it begins to ask where it came from.”

source: https://www.ted.com/talks/jill_tarter_join_the_seti_search (@ 3:02)

yieldcrv 4/15/2025|||

I think this is not too difficult for humans to comprehend, it just doesn't address the resource appropriation and geographic property claims on this planet. Aside from generational interest, conflict areas tend to have something obviously appealing about them, so there's nothing that a bigger picture nihilism helps with.

jajko 4/15/2025|||

Too idealistic view on human nature. We discovered vastly different cultures in the past, no hint of humility (rather exact opposite) or bonding, unless we find a common enemy.

Wobbles42 4/15/2025||

Taken cynically though, is this quote not simply describing the ultimate common enemy?

ndsipa_pomu 4/15/2025|||

It's an appealing idea, but surely there'd be insurmountable problems with the distance/time involved for any part to communicate to another part? It'd be like trying to run a computer with a clock that takes millions (billions?) of years to make a single tick. I just don't see that it's at all feasible and that's without even trying to guess as to how different parts can change behaviour depending on its environment (one commonly used requirement of "life").

dkersten 4/15/2025|||

What’s wrong with it taking a billion of our years to tick? Just because we, smaller than microscopic beings compared to the size of the larger structures we observe, find it to be a vastly long time, doesn’t mean that it’s a long time for something the size of the observable universe.

For a single bacteria cell, our timeframes must seem immense too.

I’m not saying it’s particularly likely, but it’s a trap to think that just because you can’t fathom the scales that makes it impossible. The universe is huge and very very old. It can afford to wait what is a long time to us for something to happen.

I do think you’re likely right in practice though, and that it is too long for the universe to be an organism. But who knows. We already know that mathematically speaking the heat death of the universe looks identical to a very zoomed in big bang, maybe we just need to zoom out a few billion orders of magnitude to see the big picture, where the vast distances and time scales we see appear as little more than micrometers and microseconds apart…

ndsipa_pomu 4/15/2025||

The problem with zooming out is that the speed of light sets a specific size/time scale so the more zoomed out you get, the more disconnected the big picture is. The observable universe is a mere 93 billion light-years across, so there's a limit on how far it makes sense to talk about zooming out. Also, with the universe expanding, the observable size will reduce over a long time period.

The scales involved are vastly different than the minor difference in scales between bacteria and us - we don't have to worry about the speed of light for anything that we currently consider alive.

daxfohl 4/15/2025|||

Not to mention, the signal strength seems too weak and unstructured to be useful as a basis of any higher order machination. A supernova is unlikely to cause much of anything outside of its immediate vicinity. Unlike neural pathways that are highly structured and mostly lossless, radiation disperses out in all directions and weakens with the square of the distance.

Unless there's something big we're missing. Maybe the cores of stars contain the final ingredient required for DNA formation or something.

mrep 4/15/2025|||

> The observable universe is a mere 93 billion light-years across

As a non-astronomer, that number still always boggles my mind.

> Also, with the universe expanding, the observable size will reduce over a long time period.

Also boggles my mind. Also makes me think of doctor who when the stars start disappearing. I need to rewatch that...

tialaramex 4/15/2025|||

> a clock that takes millions (billions?) of years to make a single tick

Much worse than that, the universe is enormous and it is expanding faster than the maximum possible velocity, as a result such a clock could never complete a single tick.

SwtCyber 4/15/2025|||

There's something kinda poetic (and maybe even logical) about the idea that what we perceive as scattered galaxies and physics is actually just the internal processes of something far bigger than we can comprehend.

jxf 4/15/2025|||

Poetic, or maybe Lovecraftian. A lot of "cosmic horror" has the trope of vastnesses too big to comprehend, where even trying to think about it (or in some cases merely learning of the possibility) causes you to go mad.

SwtCyber 4/18/2025||

It's like the deeper we peer into reality, the more it starts to look like fiction we were never meant to read.

ravetcofx 4/15/2025|||

Some might call that God. Or at least some form of Pantheism

aoeusnth1 4/15/2025||

Well, if physicalism is true then consciousness is a phenomenon of quantum fields, which span the universe. So yes, stretching the definition of creature, this could be interpreted as literally true.

ur-whale 4/15/2025||

Spoiler alert:

> THIRTY SUPERNOVAE PER SECOND, over the entire observable Universe.

Wobbles42 4/15/2025|

If we have events occuring at some rate in the entire observable universe, and that rate is one a human can easily visualize (e.g. "30"), then the answer to the question "how often do supernovas occur" is probably best summarized as "almost never".

state_less 4/15/2025||

Reminds me of the last lines of the diamond sutra.

> So you should view this fleeting world—

A star at dawn, a bubble in a stream,

A flash of lightning in a summer cloud,

A flickering lamp, a phantom, and a dream.

jl6 4/15/2025||

Ah, the good old column naming convention from MS Excel. Now there’s an amazing creation that occasionally explodes catastrophically.

didgetmaster 4/15/2025||

Two questions come to mind.

1) When was the last supernova observed in our own galaxy?

2) How close would one have to be to be observed with the naked eye?

ardel95 4/15/2025|

1604. One could say we are overdue. I’m not sure about dust or other obstacles blocking it, but based on brightness alone a supernova in our galaxy should be visible with naked eye.

ahazred8ta 4/15/2025||

1604? Sort of; SN 1987A was visible to the naked eye at 3rd magnitude. It was in the Large Magellanic Cloud, which is almost in our galaxy but not quite. 170k light years. https://en.wikipedia.org/wiki/SN_1987A

coryfklein 4/15/2025||

Near the top he shows two photos of the Cartwheel galaxy, one from 2014 and one from 2021 with the caption:

> Can you spot Supernova 2021 axdf?

Are you supposed to be able to spot the supernova?

All I've noticed is a couple of small stars that disappear in the latter photo, but this mostly seems to be because it's more blurry.

piaste 4/15/2025||

Use the cross-eye trick to superimpose the two pictures, then it becomes quickly noticeable as it will appear to blink.

pansa2 4/15/2025||

Bottom-left corner

deadbabe 4/15/2025||

Can the thread title be rewritten to be less obnoxious? “How many supernova explode every year?” is fine. This isn’t Reddit. Thread titles should not imply some kind of personality or use cliche meme speak. The all caps is definitely an abomination.

fooker 4/15/2025||

Please read the article along with bikeshedding titles. It's a good one.

bonoboTP 4/15/2025|||

The article itself is also written in that kind of quirky meme personality tone. I guess some find it relatable and humorous. Others (like me) find it obnoxious. Matter of taste or perhaps of age bracket. This is the text version of "Youtube voice", which is also evidently successful but not all like it.

deadbabe 4/15/2025|||

No. The title sounds like low effort clickbait trash.

9rx 4/15/2025||

Clickbait is appealing. This sounds like the opposite.

Timwi 4/15/2025||

Agree. For the record (in case it gets changed), the title at time of writing is “Wait. HOW MANY supernova explode every year?”.

lifeisstillgood 4/15/2025|

No wonder the Millennium Falcon takes so longer to calculate its jump to hyperspace.

Tens of thousands a year is one an hour!

There are so many supernovae you really could bounce too close to one and that would end your trip real quick

ninkendo 4/15/2025|

Star Wars takes place entirely within one galaxy, and the number of supernova per galaxy is something like 1 per century, so, nah, Han was just bullshitting to stall for time while his busted-ass computer cobbled together numbers.

wruza 4/15/2025|||

Most movies don't even leave our stellar vicinity, because they want to use hyped star/constellation names and these are from the very local set of stars. Not only a naked eye sees only around a few thousands stars, but most of them are basically next door. The mean distance to the star that you can see is <1% of galaxy size. Almost everything you see is in a 10px circle on the 1080p fullscreen galaxy map.

IggleSniggle 4/15/2025|||

Not only that, it happened a long long time ago. I'm no astronomer; would that be more or less supernovae?

Wobbles42 4/15/2025||

Indeed. They didn't say it happened an "int" time ago. They didn't even say a "long" time ago. They said a "long long" time. I'd have to pull up a copy of the C standard to be sure, but even if the units of "time" are plank times, I suspect the implications could easily be that the story occurs before the big bang.

BenjiWiebe 4/15/2025||

I suspect you're thinking of a double (floating point). A long long is only a 64 bit integer.

2^64 planck times is 9.9e-25 seconds. Planck times are really tiny.

2^64 nanoseconds is 584 years.

Wobbles42 4/23/2025||

Oh, you're right! I do remember doing this calculation with integers at some point. I might have been using something like a UUID as my bitfield length.

The context was timestamps -- I (playfully) figured out how many bits we'd need to count Planck times before the expected heat death of the universe, thus being truly future proof. I was expecting the answer to be a rediculous number, but in fact it was more in the "not efficient, but definitely feasible" range.

Floating point gets us there too, of course, but it has its own drawbacks and it isn't nearly as funny.

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