I bet you didnt know that

Baggly

Deleted User wrote: »

22/7 will repeat indefinitely if written as a decimal, 3.1428571428571428.... Pi is irrational so has no end and won't end up repeating digits.

No-one can know that for sure.

Fourier

Pter wrote: »

No-one can know that for sure.

You can prove it is true mathematically.

Is the actual value known (or is it even knowable)
I had always thought that 22/7 was the actual number but it just didn't lend itself to being expressed decimally.

This is a cross with Buttonftw, but basically if something's digits repeat at some point, then it is a fraction, just not suited to decimal expression, e.g.
1/7 = 0.142857142857142857.....

Others, like pi, are not fractions, so their decimals don't repeat.

It's knowable in that there is a formula for working out the digits as far as you want to get, obviously at some point though you'll hit the limit of what computers can do.

There are numbers "worse" than pi though that don't have a formula for working out their digits and you can prove there is no formula that will ever be found, like Chaitin's constant.

Capt'n Midnight

Pter wrote: »

No-one can know that for sure.

eisenberg1

There is a new illegal drug on the market, very popular at raves and music festivals, it’s called emcee squared.

Apparently it’s the same as E.

Baggly

Fourier wrote: »

You can prove it is true mathematically.

How can you prove it has no end or not? The only way to prove it has an end is to find the end of it. To prove it has no end you would have to keep going until......well forever, as by definition there would be no end; thus it cant be proved.

ohnonotgmail

Pter wrote: »

How can you prove it has no end or not? The only way to prove it has an end is to find the end of it. To prove it has no end you would have to keep going until......well forever, as by definition there would be no end; thus it cant be proved.

you cant say you didnt ask



https://en.m.wikipedia.org/wiki/Proof_that_%CF%80_is_irrational

Baggly

ohnonotgmail wrote: »

you cant say you didnt ask



https://en.m.wikipedia.org/wiki/Proof_that_%CF%80_is_irrational

Thats fair.

I mean i cant follow it at all, but i trust Fourier's word and yours that this checks out and isnt some massive mathmatical conspiracy by lads looking to get their names on theorems.

Ten of Swords

Shpud2 wrote: »

Loving all these frozen in time places.

Plymouth City in Montserrat is the only Capital City of a political entity that is now a ghost town. The capital and surrounding towns were evacuated in 1995 following the severe eruption of the Soufrière Hill volcano. In 1997 the lower half of the island was evacuated permanently due to a second eruption and remains permanently off limits due to seismic activity.




The government relocated to the town of Brades and a new purpose built capital called Little Bay is under construction however Plymouth is still legally the capital.

Buford T. Justice XIX

Today in 1925 Adolf Hitler's manifesto Mein Kampf was first published.

Hungrycol

The Woman who survived a plane crash reminded me about this guy: Frane Salak

Selak's brushes with death started in January 1962 when he was riding a train through a cold, rainy canyon and the train flipped off the tracks and crashed in a river. Someone pulled Selak to safety, while 17 other unfortunate passengers drowned Selak suffered a broken arm and hypothermia. The next year, during his first and only plane ride, he was blown out of a malfunctioning plane door and landed in a haystack; the plane crashed, killing 19 people. However, there is no report of any plane crash in Croatia in 1963. Three years after that, in 1966, a bus that he was riding skidded off the road and into a river, drowning four passengers. Selak swam to shore with a few cuts and bruises.

In 1970 his car caught fire as he was driving and he managed to escape before the fuel tank blew up. Three years later, in another driving incident, the engine of his car was doused with hot oil from a malfunctioning fuel pump, causing flames to shoot through the air vents. Selak's hair was completely singed in this incident, but he was otherwise unharmed. In 1995, he was struck by a bus in Zagreb, but sustained only minor injuries. In 1996 he eluded a head-on collision with a United Nations truck on a mountain curve by swerving into a guardrail, which gave way under the force of his car; he was ejected from the car when the door flew open, (he wasn't wearing a seatbelt) managed to hold onto a tree, and watched his car plummet down 90 metres (300 ft) into a gorge.

The then 2003 he won the lottery!

https://en.wikipedia.org/wiki/Frane_Selak

AllForIt

As we know the moon orbits the earth and the earth orbits the sun. But that's now where the orbiting ends.

The solar system (our sun and it's planets) also orbits around the centre of our galaxy.

It takes 250 million years for our solar system to do just 1 orbit.

If we went back in time just 1 revolution we would end up back at the beginning of the triassic period, the beginning of the dinosaur era. A lot has happened in just 1 revolution.

The solar system has only orbited in the galaxy 8 times since it's birth. So is the solar system moving slowly? No - it travels at approx 500,000 miles per hour.

Given the speed it travels at that gives one some idea of how big our galaxy is no mind the universe.

sbsquarepants

Reminds me of the story of Aussie truck driver Bill Morgan.

He was involved in a crash, serious enough but not life threatening - however while being treated in hospital he took an allergic reaction to some medicine and died.
He was "dead" for 14 minutes but the docs managed to get his heart going again. Docs expected the worst, he remained in a coma for about a fortnight, but when he regained consciousness he was surprisingly unharmed, no brain damage or anything like that.
After leaving hospital he decide to change his whole life around, change his job and ask his girlfriend to marry him. She said yes and to celebrate he treated himself to a scratch card - and duly won a car.
Now, a local TV station caught wind of this and asked him to re-enact it for a little good news segment "Man comes back from the dead to win car" kind of thing.
While filming the re-enaction they went back to the same shop and recorded him buying another scratchcard - this time he won $250,000!

Ten of Swords

In 2014 scientists from MIT and NASA demonstrated that they could transmit a wifi signal to the moon using four telescopes in New Mexico. The telescopes are each 6 inches in diameter and are channeled by a laser transmitter that beams information in coded pulses of infrared light. They transmit an uplink signal to a satellite orbiting the moon. Earths atmosphere bends the signal as it travels to the moon so the four telescopes transmit the light through different columns of air, each one with a different bending effect. This ensures that at least one of the beams will establish contact with the receiver and establish a connection with the moon. The scientists sent data from Earth to the moon at a rate of 19.44 megabits per second and a download rate of 622 megabits per second.

I thought this was an amazing feat, even though nobody has been to the moon since the 70s!

Skylinehead

Ten of Swords wrote: »

In 2014 scientists from MIT and NASA demonstrated that they could transmit a wifi signal to the moon using four telescopes in New Mexico. The telescopes are each 6 inches in diameter and are channeled by a laser transmitter that beams information in coded pulses of infrared light. They transmit an uplink signal to a satellite orbiting the moon. Earths atmosphere bends the signal as it travels to the moon so the four telescopes transmit the light through different columns of air, each one with a different bending effect. This ensures that at least one of the beams will establish contact with the receiver and establish a connection with the moon. The scientists sent data from Earth to the moon at a rate of 19.44 megabits per second and a download rate of 622 megabits per second.

I thought this was an amazing feat, even though nobody has been to the moon since the 70s!

Trying to understand this, is the data sent up through a laser? Because if it is, it isn't WiFi, WiFi is a specific electromagnetic frequency, laser is a different one. Still cool of course.

Ten of Swords

Yes, you're right. The article I read misinterpreted the source doc and called it wifi, the source doc called it a wireless connection. The technology is called Lunar Laser Communication Demonstration (LLCD)

It's still a very cool achievement I think and vastly outperformed radio transmissions

Source https://www.osa.org/en-us/about_osa/newsroom/news_releases/2014/first_broadband_wireless_connection%E2%80%A6to_the_moon_!/

Peregrine

AllForIt wrote: »

As we know the moon orbits the earth and the earth orbits the sun. But that's now where the orbiting ends.

The solar system (our sun and it's planets) also orbits around the centre of our galaxy.

It takes 250 million years for our solar system to do just 1 orbit.

If we went back in time just 1 revolution we would end up back at the beginning of the triassic period, the beginning of the dinosaur era. A lot has happened in just 1 revolution.

The solar system has only orbited in the galaxy 8 times since it's birth. So is the solar system moving slowly? No - it travels at approx 500,000 miles per second.

Given the speed it travels at that gives one some idea of how big our galaxy is no mind the universe.

500,000 miles per second doesn't sound right. Should be in the order of a few hundred km/s.

The observed rotation curve of the Milky Way — which shows the relationship between the orbital speed of stars and gases vs their distance from the centre of the galaxy) — doesn't follow the expected curve. The speeds are much higher at large radii and the system shouldn't be gravitationally bound. This suggests that there is more matter present in the galaxy than the matter we observed and used in our predictions.

Enter stage dark matter theory. Similar observations are made for all spiral galaxies and galaxy clusters. Ellipticals are more complicated but evidence for dark matter can be inferred from other methods there too.

Professor Moriarty

Peregrine wrote: »

500,000 miles per second doesn't sound right. Should be in the order of a few hundred km/s.

The observed rotation curve of the Milky Way — which shows the relationship between the orbital speed of stars and gases vs their distance from the centre of the galaxy) — doesn't follow the expected curve. The speeds are much higher at large radii and the system shouldn't be gravitationally bound. This suggests that there is more matter present in the galaxy than the ones we observed and used in our predictions.

Enter dark matter theory. Similar observations are made for all spiral galaxies and galaxy clusters. Ellipticals are more complicated but evidence for dark matter can be inferred from other methods there too.

I think I'll start a new thread. 'I bet I you won't understand that.'

wally79

Peregrine wrote: »

500,000 miles per second doesn't sound right. Should be in the order of a few hundred km/s.

The observed rotation curve of the Milky Way — which shows the relationship between the orbital speed of stars and gases vs their distance from the centre of the galaxy) — doesn't follow the expected curve. The speeds are much higher at large radii and the system shouldn't be gravitationally bound. This suggests that there is more matter present in the galaxy than the ones we observed and used in our predictions.

Enter dark matter theory. Similar observations are made for all spiral galaxies and galaxy clusters. Ellipticals are more complicated but evidence for dark matter can be inferred from other methods there too.

Correct. From Wikipedia

“The galactic year, also known as a cosmic year, is the duration of time required for the Sun to orbit once around the center of the Milky Way Galaxy.[1] Estimates of the length of one orbit range from 225 to 250 million terrestrial years.[2] The Solar System is traveling at an average speed of 828,000 km/h (230 km/s) or 514,000 mph (143 mi/s) within its trajectory around the galactic center,[3] a speed at which an object could circumnavigate the Earth's equator in 2 minutes and 54 seconds; that speed corresponds to approximately one 1300th of the speed of light.”

aoh

On a similar buy very different note: I remeber reading years ago about a couple whose wedding went very wrong. Venues were double-booked and photographer never showed up. A red-top heard about it and decided to give them a second chance. Everything (except the actual marraige obvoiusy) was duplicated. Everything went swimmingly until they left. Car crash. Bith killed!!

New Home

That's what happens when "For better, for worse, in sickness and in health, till death do us part" is taken too seriously...

Capt'n Midnight

Ten of Swords wrote: »

In 2014 scientists from MIT and NASA demonstrated that they could .. sent data from Earth to the moon at a rate of 19.44 megabits per second and a download rate of 622 megabits per second.

In 2014 ESA were using 1.8 Gbit/s laser link to transfer data between Sentinel-1A and Alphasat, two satellites in orbit and the ground.

NASA are way better at PR.

AllForIt

Peregrine wrote: »

500,000 miles per second doesn't sound right. Should be in the order of a few hundred km/s.

Yes correct it's 500,000 miles per hour, not per second. That's 3,600 times slower than I said it was. No wonder it takes so long to do one revolution

Salthillprom

Ten of Swords wrote: »

I thought this was an amazing feat, even though nobody has been to the moon since the 70s!

Nobody has ever been on the moon.
Why haven’t they been back since? 🤨🤔

Water John

Bridensteine Head of Nasa, has just said there going back to the moon.

maccored

quite a few cats and kittens are lactose intolerant

Kat1170

maccored wrote: »

quite a few cats and kittens are lactose intolerant

As are hedgehogs.

Capt'n Midnight

Water John wrote: »

Bridensteine Head of Nasa, has just said there going back to the moon.

They've been saying that for decades. Bush said it too. And Bush. And Obama.

One critical path is the Exploration Upper Stage for the SLS.
It uses RL-10 engines, which have been putting satellites into orbit since 1963.


Spending billions to "develop" flight proven hardware ?

It's just a boondoggle.

Capt'n Midnight

Hedgehogs ?

Why can't they share :rolleyes:



Why did the hedgehog cross the road ?
to see his flatmate.



Hedgehogs tend to have fleas because they can't groom so easily.

New Home

Capt'n Midnight wrote: »

Hedgehogs ?

Why can't they share :rolleyes:

Why did the hedgehog cross the road ?
to see his flatmate.

Don't know whether to groan, boo, or slow clap, Capt'n. Bravo.

Peregrine

Professor Moriarty wrote: »

I think I'll start a new thread. 'I bet I you won't understand that.'

Sorry, I'm ****e at explaining things :pac:

Basically, when AllForIt posted about stars orbiting the centre of galaxies, I thought you should know that there were discrepancies between the observed orbital speeds of stars in galaxies and the speeds we predicted using everything we know about motion. This discrepancy was one of the major pieces of evidence for the existence of dark matter.