The Astronomy Thread
- Thread starter Araxen
- Start date
- 31,867
- 125,062
Just read about starlink. That's fuckin amazing. We are super sure it wont be used as a control mechanism when the leftists take the reigns back, ya?
Last edited:
meStevo
I think your wife's a bigfoot gus.
- 6,373
- 4,648
The biggest concern w/ Starlink is the possibility that there will never be a 'clear' night sky again when you might be able to see 20 of these at a time overhead. Terrestrial-based astronomy and astrophotography may never be the same also.
- 1
Ukerric
Bearded Ape
- 7,920
- 9,571
C, the speed of causality, appears to be absolute. What Bell's Theorem states is that you cannot predict correctly every event in a local context only - you need access to knowledge of some states that are not within your light cone. Entanglement is the mechanism by which those external states affect the local context, but those states cannot transport causality (that is, you cannot manipulate those external states before they affect the local state).
Simple explanation: You entangle two photons so that they have opposite polarization, then send them in opposite directions of each other. Those two photons are now outside of each other's light cone, and so any action on one photon cannot affect the other directly.
You can predict that polarization of one photon is either of the two possible. Bell's Theorem, if true, says that you cannot predict the polarization any better than that without having access to the exact polarization of the second photon which is outside of your light cone (non local information). If false however, there might be an internal (hidden) variable that let you correctly predict the photon's polarization based on the entanglement event itself (which is within your lightcone, since the photon came from there) without requiring to measure the other photon.
The point is that you cannot manipulate the photon to specify which polarization it has - you can only measure it. Once you measure it, you know that the opposite photon has the opposite polarization, but you still haven't been able to affect it. Therefore C remains involate: your cause (the measurement) hasn't created an effect (the opposite measurement) outside of your light cone.
- 2
- 4,107
- 4,043
Ukkeric I really like the definition of C you gave. That helped sharpen things for me a bit.
This is from wikipedia but it just really blows my mind to try to hash it out conceptually:
"No physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics."
It is the idea that LHV (the cone of light, the idea of location as relative to the constant C) cannot account for quantum predictions that is really hitting me hard. That is where calling C the speed of causation (its maximal value, outside of a vacuum, C naturally decreases) is really helpful. It sharpens the problem. Bell's theorem would claim certain verifiable phenomena (entanglement) occur in a system not governed by C.
I like being confused like this.
This is from wikipedia but it just really blows my mind to try to hash it out conceptually:
"No physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics."
It is the idea that LHV (the cone of light, the idea of location as relative to the constant C) cannot account for quantum predictions that is really hitting me hard. That is where calling C the speed of causation (its maximal value, outside of a vacuum, C naturally decreases) is really helpful. It sharpens the problem. Bell's theorem would claim certain verifiable phenomena (entanglement) occur in a system not governed by C.
I like being confused like this.
meStevo
I think your wife's a bigfoot gus.
- 6,373
- 4,648
The sensationalist headline is 'Jupiter's great red spot is going away!' - but what we do know for now is that there are big changes occurring, not sure if they're longer term changes or not yet. The storm has been encircled by this brown band and appears to be diminished somewhat as high level jet streams strip some of it away.
Another article: See Jupiter's Great Red Spot Unfurl in Your Scope - Sky & Telescope
Included image from above link:
Another article: See Jupiter's Great Red Spot Unfurl in Your Scope - Sky & Telescope
Included image from above link:
- 5
Ukerric
Bearded Ape
- 7,920
- 9,571
There's a PBS episode on youtube that goes a bit deeper into that. The point is that light goes at the speed of causality rather than causality going at the speed of light (any massless interaction goes at the maximum speed possible, i.e. speed of causality, not just light).
Our comprehesion of the universe is shaped by being adapted to the simple life of Savannah-dwelling primates. The universe itself is... different.
- 4
Tripamang
Naxxramas 1.0 Raider
- 5,196
- 31,735
While it can provide internet to people in remote regions the real long term value of this is a second backbone in the sky that will provide lower latency connections than ground based fiber optics especially to some of the more remote regions of the world. The more satellites you have up the larger the overall bandwidth of the network because it can route the data through the satellites via different paths. Second to that farmers, boaters, air planes etc will all the find the network of high value, and I know shipping companies already pay a fortune for network access that's barely faster than early 90's dial up. This is going to generate a lot of revenue, especially if they can get theirs built first as OneWeb and I'm sure others are planning their own constellations to compete.
If this ends up being the windfall the industry says it will be you'll be looking at SpaceX efficiency with NASA sized budgets but instead of all the science it's going right into rockets. It's a real bright future.
- 2
Big Phoenix
Pronouns: zie/zhem/zer
- 44,624
- 93,216
Siddar
Bronze Baronet of the Realm
- 6,340
- 5,864
I just spent three days trying to understand Bell's Theorem
Bell's theorem - Wikipedia
en.wikipedia.org
I cannot grasp most of its claims, but one of its claims does ring too clear: if it is correct, local realism is simply incomplete.
That conclusion, which stems from this idea of quantum entangelment, renders the absolute C (speed of light) as not absolute, since entanglement can happen / be detected at infinite greater than light speeds.
Three days. I am not that smart. Bell's Theorem just gave me a headache. If the theorem is right, Einstein is wrong?
Distance is not a fundamental law of the universe.
iannis
Musty Nester
- 31,351
- 17,656
Distance has to be a property of other things.
It's kind of like it you're on a ship at sea travelling from one point to another. There is a fixed and non fixed distance between those two points, both are accurate depending. The journey is always longer than the fixed distance. you have to go up and down the waves.
That only illustrates how the concept of distance can not be constant and if it is variable we have to question of it is fundamental. It seems like variable funda!metals would be possible, but distance can be Reduced and explained with time and motion.
Explaining it that way leads you into REALLY weird places though.
- 1
Siddar
Bronze Baronet of the Realm
- 6,340
- 5,864
Distance is a rule not law because it only came into existence after the creation of the universe.
Trace all things back to the beginning and all thing were close together and have spread out.
Quantum entanglement is the result of that state at the beginning when there was no distance between things.
Ether that are it just magic.
Trace all things back to the beginning and all thing were close together and have spread out.
Quantum entanglement is the result of that state at the beginning when there was no distance between things.
Ether that are it just magic.
Last edited:
- 2
Tuco
I got Tuco'd!
- 45,422
- 73,489
It's a pretty huge business question for sure. I'd be very curious to see what calculations they have internally to show that a market exists to provide the kind of funding they expect to get. I don't really trust their published numbers for numerous reasons. Lots of unknowns on both the market demand and the true installation and operational costs for Starlink.
Tuco
I got Tuco'd!
- 45,422
- 73,489
I don't really buy that ~0% figure though, satellites are easy to spot
Last edited:
- 31,867
- 125,062
That starlink deploy last night was cool. Looked like a train as they were ejected out of the capsule.
Last edited:
- 1
Borzak
Bronze Baron of the Realm
- 24,609
- 31,935
They show up in astrophotography pretty easily maybe less when you're tracking an object and expose an hour or more of short explosures stacked together.
- 1
- 31,867
- 125,062
