Monkfich t1_jb2idvd wrote

When people say “the edge of the universe” they actually mean “the edge of the visible universe”. Why? It’s a combination of the (constant) speed of light and the rate that objects (galaxies for this example) fly away from each other in the universe.

Say a galaxy beside us is moving away at 2 kilometres (we’ll use km, 1000m, instead of miles as miles doesn’t really fit in with science very well) per hour, then another galaxy further on is moving at 4 km per hour from our viewpoint in galaxy 1. Galaxy 2 sees both galaxy 1 and 3 moving away from it at 2 km per hour, and galaxy 3 has a similar view to galaxy 1, but for it it looks like we’re the ones travelling away from it at 4 km per hour.

And as these galaxies move away from each other, that 2 km/hr is no longer true, and speeds start to get faster and faster.

So objects in the universe are not just moving away from each other, they are also accelerating away from each other.

Now let’s take that logic and take us thousands of km/ph, then millions of km/ph, then billions of km/ph, and beyond…

Then we get to the speed of light. The speed of light per second is easy to find but gets even more massive when talking about light in km/hr.

1.08 x 10 to the power of 12 km/hr or 1,080,000,000,000 km/hr

That’s a trillion km/hr. And we’re now at the edge of the visible universe - 46.5 billion light years away.

When objects are flying away from us an inch / cm / etc faster than that, we will never see them again. And of course, that object is continually accelerating, so of course it is going faster than that already.

And why don’t we see them? If an object is moving away from us faster than the speed of light, then the light emitted by that object will continue to be emitted, but it will never ever reach us … it didn’t and it can’t go fast enough.

What we see as things get closer to the edge of the universe is that they get massively red shifted, then when they get to the edge, it’s a bit like a black hole - things will appear to get fainter, then as they approach and cross horizon, they will infinitely slow down and appear to stop, then fade away. Or I assume they can’t fade completely, so all objects that ever passed the horizon will be visible on it, just incredibly faint, and effectively gone.

That galaxy that has just sadly disappeared from our view is … ok (or at least it wasn’t affected by a visual effect only experienced by us). That galaxy will have it’s own visible universe, and has just seen our Milky Way slow down, stop, and get continually fainter. And similarly, every object in the very likely infinite universe (very likely, as we can’t observe it for ourselves, snd never will) will experience it’s own individually experienced visible edge of the universe.

Over time, we will see more and more galaxies travel over that horizon, and one day in the far flung future, we’ll not see any other galaxies or objects outside of the milky way (or Milky Way and a few other galaxies linked together by a gravitational force stronger than the expansion rate - these galaxies including the milky way are known as the Local Group). Beyond the stars of the Local Group, it will be dark, and it always will be.

Will that force pulling apart galaxies impact the galaxies themselves - will galaxies be destroyed as stars find that expansion force to be higher than the gravitational force acting on them?

The current theory here is that the expansion rate isn’t big enough for that to happen, but scientific debate changes - or is enhanced - in this field all the time. It’s really interesting stuff!


Monkfich t1_jazybyt wrote

Can we convince Putin and his cronys that this is the successor to wikipedia, and he needs to make all his history-changing modifications on that site, rather than the old one. Noone will even stop him this time!


Monkfich t1_ja8x0av wrote

Don’t make the mistake of thinking that europe and the west is doing the wrong thing by only using it’s “bark”. If it were to bite, it would create a huge escalation not just in Russia, but across cities and towns (non-strategic too, Putin like to pick them and blow them up to make a “point”) which would create a wartime population. On the event of decisions to send massive forces to Ukraine, Putin may decide to use heavier weapons , heavier shells, heavier missiles, and we know he likes to throw bodies at a problem.

Arguably Putin wouldn’t surrender/cancel his special operation even if pushed back to the borders by a larger and stronger force. He is an evil fucker but he knows how to play an enemy and wait them out. Or maybe the new Allies push forward to Moscow to topple Putin there? Extra escalation and as an attack has now been made on Russian soil, all Allied countries can expect an attack on their soil too.

And Belarus? Their army will likely support perceived attacks on their own soil, to get them into the wider war. We had that attack today, and Putin can orchestrate more.

We “all” want Ukraine to win, but it won’t win by creating nuke targets inside and outside of Ukraine. The Allied countries maybe aren’t biting directly, but they are sending an awful lot of equipment, weapons, and ammunition to Ukraine.


Monkfich t1_ja8nqz1 wrote

It’s not inevitable that Belarus gets directly involved, and if they do it opens a huge amount of border to defend against. It’s not a border to go across and bring battles towards the Belarus capital, but instead makes the country need much more manpower to defend than currently, which is better spent defending elsewhere and better still - attacking, and taking back land.

So it’s not a war they can push forward on initially - initially it’ll be an attempted massive push by Belarus and Russia. And if Belarus gets directly involved it will be a massive setback, thinning the Ukrainian defence, ruling out the ability to strike back, and minimising the big morale boosts when towns and cities are retaken.

The article says that Russia has no comment on this, but like every single attack on them, they will use it as an opportunity, e.g. find any non-strategic town that the two Belarusians allegedly fled to, then destroy it with barrages for two weeks.

I get the thumping of the chest, the feeling of striking back, and making the enemy power bleed. But it needs to be coordinated with official forces or it risks everything.


Monkfich t1_j9swy5k wrote

I’ve seen estimates of an average of 100 tonnes per day of meteorites and space dust entering earth’s atmosphere every day, and if we add on avg ca 28 tonnes more per day for the satellites, it doesn’t significantly change mass.

Like the other commenters though, a range of other factors needs to be considered.


Monkfich t1_j1lueur wrote

Can confirm this works - I once had a treasure hunt using our Amazon Alexa dots - all bought cheaply on sales, and one in each room. My son would start in the living room, ask Alexa a keyword phrase to start, then the dot will give him a new clue and a room to take the answer to. He’d go to the next room, say, “alexa, the answer is xyz”, and if he got it right (and to the right dot), the dot would recognise it and give the next clue.

About 10 clues later he got a reward - good fun that doesn’t take huge amounts of money, and many households have a fair few alexa things kicking about by now.