Recent comments in /f/askscience

Teo_Filin t1_jb1o0zq wrote

Reply to comment by PercussiveRussel in Does the age of the universe depends on where you are? by _bidooflr_

Cool! So no way for instant info exchange? Such a pity.

Though I can't accept "information" as physical measure at macro-level (it's our description of some properties), just at quantum-level (numbers defining a particle).

I even doubt that time is a coordinate meaning some "future" and "past" do exist as places we can visit (present is real with some intensity of processes influenced by gravity and speed; future is our anticipation, past is our memory).

I'm not deep in advanced physics and higher mathematics, just evolving my perception and checking cosmology with common sense sometimes.

2

adaminc t1_jb1m0mj wrote

Reply to comment by intromission76 in Why does Chronic Wasting Disease(CWD) makes deer skinny, even if they eat? by Canisventus

Tongue hanging out, excessive slobbering, being a bit listless while walking similar to someone that is drinking alcohol, looking thinner than they should be. Other than that, you can't tell if it has CWD, and just have to hope it doesn't.

That said, you can chop off the head, and send it in to local facilities that will test it, this is actually encouraged, so the authorities can better map infected populations. In the meantime, you just let the meat sit in your freezer until they report back.

7

Possible-Quail-7376 t1_jb1lnvt wrote

Reply to How exactly does ocean acidification inhibit the formation of calcium carbonate in marine organisms? by fr140

i understand this problem perfectly from different point.. when i grow weed, the younglings are most vulnerable to ph changes (absorbtion balance of minerals, nutrients..) oh and balance of bacteria in medium aswell. Point is, tap water without letting it sit is enough to mess up the balance, and you notice the difference. growth might be hindered or the plant dies alltogether.. Ph is everything.

anyway, id imagine sea life being even more directly vulnerable since there is no medium (buffer) in between.

2

PercussiveRussel t1_jb1kli4 wrote

Reply to comment by Teo_Filin in Does the age of the universe depends on where you are? by _bidooflr_

I don't know a lot about cosmology, but I do know about quantum and relativity.

This is a very interesting question! The best way I 'mangle' entangled particles into relativity is to avoid it all together. This is based on the fact that, in order to know about the simultaneity of entangled particles, you'd need a classical channel to transfer information.

Take this experiment: you and I have an entangled particle pair (that's either in AA or BB) and we're lightyears apart. I measure my particle and measure it to be in state A. This means I know yours is in state A too. However, I don't know whether mine is in state A because you collapsed it to be in A, or whether I was the first and have therefore collapsed yours to A. There is no "now your particle is in A" because it could've been there for years (depending on how long ago we separated the particles). The only thing that my experiment proves is that now I know that your particle is in state A. In this way, it's safe to say there is no real simultaneity occurring. This is one of the more prevalent explanations at the moment and one that I personally believe is the most robust since it doesn't require us to completely rip up either relativity or quantum (which are both among the most verified theories we have)

​

In other words: to me relativity describes the speed of information. Entangled particles don't break this speed as no information is changing hands. This means there is no shared now between the particles.

(The math also shows this, the order of observations is symmetric (they commute), so they have no impact with regards to causality. No causality = no "now")

Edit: To clear something up, for those who don't live and breathe this stuff: entangled particled are two or more particles that share a common set of states. A "quantum object" (which is not a scientific term, but I'll use it anyway) can occupy a quantized (meaning discrete) set of states. When the object is said to be in a superposition, this object is in an undefined state, where it has an x% chance to be in state A, a y% chance to be in state B etc. When we measure the state of this object, it "chooses" one of these states at random and will be that state.

An entangled state means that two seperate objects share a combined superposition. This means that there are less possible states than just all possible permutations. Eg: two objects who can each be in state A or B and are not entangled if they're in the following (equally likely) superposition: AA, AB, BA and BB. Knowing that the first one is A leaves us with the following possible equally likely states: AA and AB. We know precisely nothing about the second object from knowing the first.

Now an entangled object removes some of these possible states. For example the particles are in a superposition of AA, AB or BB. Now knowing that the first one is B tells us that the second one has to be B too. Knowing the first one is A leaves us with no knowledge on the second one. (they're still entangled though, even if the AA and AB states are really useless)

This is "all" entanglement is. It's not something whereby moving the first from state A to B automatically moves the second one from A to B too.

Since you can't control the outcome of a random measurement, there is no way to encode any information in the entanglement itself that is transported on observation. It's pure probabilistics. I mean, you could make the states in a "superposition" of AA and BA so you know the second person always gets a state A after measuring, but you need to send them the particle which goes with locality, so that's just sending an email with extra steps.

The reason that so called "quantum communication" is so interesting though, is that no one can listen in on your conversation. Take the following scheme:

We agree on the following protocol: We have an entangled pair that's in a superposition of AA and BB. I measure mine, then send you a phone call with my measurement. Then you measure your particle (and therefore verify my phone call, beceause our measurements have to be the same).

If I lie, I mean to transmit a 0, if I speak the truth I mean to transmit a 1

No one knows what we are talking about, because they don't know what our entangled pairs are doing. For them, when I tell you "A", it's either a 0 or a 1, with 50% chance each. However notice I do need to say something to you, because I can't affect the outcome of the observation.

I think this explanation clears up a lot about what entanglement actually is. Some people imagine it's like two switches where if you flip one, you instantaneously flip the other one. It's not.

17

Anonymous_Otters t1_jb1crzq wrote

Reply to comment by pepe_silvia_12 in Does the age of the universe depends on where you are? by _bidooflr_

The flow of time is relative, so time is flowing at different rates at different places depending on the curvature of the universe in respective locations and on relative velocity. Only when you get into the same gravity well in the same place can two objects be considered to be more or less at the same time. As soon as they leave the same gravity well or travel at different relative velocities, they are technically now in different times until they meet up again. That said, every single molecule, atom, subatomic particle is technically running at slightly different times even within the same object. Space and time are, under general relativity, considered inextricably linked, so can be thought of as the same thing. Changing space changes time, so being in even a slightly different spaces means you are in a slightly different timr. This is why the cosmic microwave background radiation is used as a universal resting position to make some sort of standard time.

202

Possible-Quail-7376 t1_jb1bhnu wrote

Reply to comment by DocJanItor in Why do cosmologists say that gravity should "slow down" the expansion of the universe? by crazunggoy47

allright but the universe as we know it might be one string, layer of whatever. looking at the big picture, anything goes really. assuming the universe is same shape as the rest of stuff (toroidal) doing same stuff as atoms, quantum particles and stuff like that on what knows dimensions..

well, i guess we live in positive side of universe since stuff seems to expand. One string in a field. perhaps that is the part what scientists would call the universe part.

to be continued...

1