Astronomers witnessed the death of a star as it happened | Hacker News Reader

Astronomers witnessed the death of a star as it happened

news.ucsc.edu

74 pointsbenbreen43 comments

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It referenced a time lapse in the article (once every 30 min) but I didn't see a video link. Did anyone else find it?

Here is all I could find:

https://www.youtube.com/watch?v=hB2QQyEyF5k

The video description says that the timelapse was taken over the course of a year

Or, about 60 million years after it happened...

It really is mindblowing when you think it actually happened 60 million years ago.

What we're doing now might be visible as 'now' to someone 60 million years into the future, albeit a bit down the road from us.

There is a frame of reference in which the event and the observation are simultaneous.

I'm rather confused by this statement. Can you elaborate?

If you move fast enough, weird things happen in special (or general) relativity.

Similarly, if you somehow managed to send something even slightly faster than the speed of light, there's a frame of reference in which you have send it backwards in time.

The photons we observed from the death of the star experienced no time between coming from the star and arriving to us.

Are you saying that if I’m in a spaceship, and I travel at the speed of light as I leave that star at that moment, and then I arrive here at earth, with my fellow photons traveling next to me, that I will have arrived at earth instantly without observing any time spent in transit?

That is correct.

Obviously, given that, you would have no way of stopping, so your arrival would be abrupt (ignoring whatever magical affects would be necessary to accelerate a massive object to light speed).

So in other words, if you can travel at the speed of light, you can be anywhere in the universe instantly, and never have to wait to get anywhere? I will say, that certainly makes no sense to me.

it's a big "if"; it's not possible for objects with mass to accelerate to light speed.

If you were able to do so, yes you could "get" anywhere in zero subjective time - as mentioned earlier, since no time passes for you, there would be no way for you to decide that you wanted to stop travelling at light speed - you would end your existence by impacting something.

> that certainly makes no sense to me

Humans, as a species, aren't experienced with relavitistic effects; we have no useful inherent intuition as to how things behave at these sorts of speeds. Most of us have to accept the maths and the experiements that demonstrate that our understanding of this behaviour is accurate.

This the reason why photons have no rest mass.

And you having a rest mass cannot ever reach the actual speed of light, only a factor of <1.

If you were to travel with 95% of the speed of light your rest mass would increase by 3.2x ... at 99% by 7.1x at 99.9% by 22.4x and at 99.99999% by 2240x and so on. The Lorentz factor is infinite for the speed of light. Time "stops" and the object contracts to "zero" at c.

https://www.1728.org/reltivty.htm

https://www.youtube.com/watch?v=wteiuxyqtoM

Yes - when you're the star itself, I suppose. That's not what GP is suggesting at all...

I don't think GP is really suggesting anything, just trying to make a clever comment with no substance.

This is definitely false according to SR, because the event is on the past light cone of the observation.

Well, from the perspective of the photons, the explosion happened just an instant before they hit the telescope, and they barely even travelled a single Planck length to get from the exploding star to the telescope. Events that are so far apart in space and time don't have fixed periods (or distances).

To observers in other galaxies that are moving fast relative to both us and the star, the time between the explosion and our detection of it (were they able to perceive both) would also vary.

Perhaps one of their planets released a probe that will attach to a future intelligent life form and tell their story. [1] How many years until we potentially find it?

[1] - https://memory-alpha.fandom.com/wiki/The_Inner_Light_(episod...

That episode is great, but manipulating an unknown and unwilling alien brain always struck me as too dangerous.

Maybe their Voyager equivalent reached the wrong aliens in the dark forest.

The Enterprise crew agreed with you. They tried twice to sever the connection, nearly killing Captain Picard in the process.

Official NASA press release

https://www.nasa.gov/feature/goddard/2021/hubble-gives-unpre...

I miss the images before and after

Yeah, always the same. Also with archeological articles. Not a picture of the find :)

That said, great article and discovery.

There should be millions of stars out there where death and birth of stars should be happening quite often.

Why are we not seeing these? Is space just too big for us tiny human beings to observe them?

Stars last a long time, so even though there are a lot of them, they don't die that often.

Some sources claim that about one star per year in Milky Way dies. We have about 100 billion visible galaxies, so roughly 3000 stars per second die in our visible universe - however, most of those are small stars which aren't really visible to our instruments.

Small stars live a long, long time. We shouldn't see them die, yet.

They were born long, long ago as well.

Red Dwarfs are expected to burn for trillions of years.

We see supernovae regularly and observe the aftermath within days of the event. What is special about this one is that TESS happened to be observing it before the explosion.

paper: https://arxiv.org/abs/2110.10742

poster: https://ui.adsabs.harvard.edu/abs/2021tsc2.confE.144T/abstra...

ahh I was hoping it was Betelgeuse

Headline is a physical impossibility to occur (if we assume astronomers in our solar system), or a practical impossibility to know about (if we assume otherwise).

Yeah, not a great headline, though they did say it was 60 million light years away, which at least alludes to the truth.

Pedantically, we can't actually witness anything at the same moment it happens for the same reasons. Our brains trick us into thinking we are... but it turns out all of us are behind the times.

I think the headline provides the necessary punch of what was so cool about this observation; "We" watched it evolve instead of just looking at the aftermath.

>Pedantically, we can't actually witness anything at the same moment it happens for the same reasons.

the best kind of antically, when I first read the title I snorted as everyone else and rushed in to observe the obvious (ironic given the subject) but your observation brought me up short - then again observations that are only milliseconds in remove from the occurrence as opposed to millions of light years may be given a pass about the 'same time' crack.

It's not only the speed of light, but also the time the brain needs to process visual inputs, and It adds up to dozens of milliseconds:

https://theconversation.com/what-youre-seeing-right-now-is-t...

If only the brain used React and the shadow DOM we wouldn't have this problem!

I think it stops being pedantic when it's a 19 orders of magnitude difference between 1ms and 60mya

Headline is meaningless: with relativity in play, "at the same time" does not even have a well defined meaning.

Headline is imo meaningless: with general relativity in play, does "at the same time" even have a well defined meaning?

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