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Boyajian's star (alien megastructure star) is dimming again right now


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20 minutes ago, A True Kaniggit said:

In this hypothetical the pole is made out of an exotic material that is super lightweight and super stiff to the point that it refuses to change its shape no matter what pressure is applied to it. So why wouldn't one end move simultaneously with the other end, whatever the distance between the two points? 

Why not just hypothesize a spaceship with an exotic engine that is super fast and super physics-defying then?  You aren't answering any questions about reality with hypotheticals.

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So I guess if you could somehow pre-compress all the atoms and keep them permanently compressed, it might just be possible.

Although this I would like to point out this is still not a signal that travels at FTL.   the signal travels at the speed this magic rod moves   its just in theory the whole rod moved simultaneously.  without somehow fracturing into millions of pieces.

 

 

I myself am not yet ready to write of FTL as impossible.  just impossible with how we understand things today.  and highly improbable.  It is nice to dream though.

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11 minutes ago, The Mance said:

Why not just hypothesize a spaceship with an exotic engine that is super fast and super physics-defying then?  You aren't answering any questions about reality with hypotheticals.

Huh? Isn't that exactly how you answer questions about reality? Come up with a hypothesis and do a crap ton of experiments until it's proven right or wrong, thus gaining an answer? 

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11 minutes ago, Pebble said:

So I guess if you could somehow pre-compress all the atoms and keep them permanently compressed, it might just be possible.

Although this I would like to point out this is still not a signal that travels at FTL.   the signal travels at the speed this magic rod moves   its just in theory the whole rod moved simultaneously.  without somehow fracturing into millions of pieces.

 

 

I myself am not yet ready to write of FTL as impossible.  just impossible with how we understand things today.  and highly improbable.  It is nice to dream though.

I would like to believe that FTL is indeed possible but it would require a fundamental change in our understanding of the universe, which I'll gladly admit is very limited. 

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8 minutes ago, Pebble said:

So I guess if you could somehow pre-compress all the atoms and keep them permanently compressed, it might just be possible.

Although this I would like to point out this is still not a signal that travels at FTL.   the signal travels at the speed this magic rod moves   its just in theory the whole rod moved simultaneously.  without somehow fracturing into millions of pieces.

And I would agree. In this scenario nothing physically is moving faster than the speed of light. However information would be delivered faster than the speed of light itself could transmit it.

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7 minutes ago, A True Kaniggit said:

Huh? Isn't that exactly how you answer questions about reality? Come up with a hypothesis and do a crap ton of experiments until it's proven right or wrong, thus gaining an answer? 

But you can't cherry pick which laws of physics apply and which don't. Your experiment must comply with _all_ the laws of physics and that include those governing the structure of matter.

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1 minute ago, Loge said:

But you can't cherry pick which laws of physics apply and which don't. Your experiment must comply with _all_ the laws of physics and that include those governing the structure of matter.

And that is what I want to know. Do the current laws of physics rule out a material that can be built into a pole that is more than a light year long. And do they state that this pole can't be so perfect in form that when pushed at one end, the other end moves simultaneously?

If such a pole were possible, would not someone moving it then be transmitting information to the other end at FTL speeds?

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24 minutes ago, A True Kaniggit said:

Huh? Isn't that exactly how you answer questions about reality? Come up with a hypothesis and do a crap ton of experiments until it's proven right or wrong, thus gaining an answer? 

Sorry, I meant *your* hypothetical.  And Loge is right.  You can't just ignore certain aspects of physics and expect to get real answers about the universe.  Right now your question reads:

 

Physics!- "FTL travel is impossible because of physical constraints A, B and C."

aTK- "but what if we construct a magical device that ignores those constraints?  Wouldn't ftl travel be possible then?"

Physics!-  "err...?"

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18 minutes ago, The Mance said:

Sorry, I meant *your* hypothetical.  And Loge is right.  You can't just ignore certain aspects of physics and expect to get real answers about the universe.  Right now your question reads:

 

Physics!- "FTL travel is impossible because of physical constraints A, B and C."

aTK- "but what if we construct a magical device that ignores those constraints?  Wouldn't ftl travel be possible then?"

Physics!-  "err...?"

But is my device really that magical? All it really boils down to is a really long stick that when one end moves, the other end moves as well.

And no, not FTL travel. But the transmission of information at FTL speeds.

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12 minutes ago, A True Kaniggit said:

But is my device really that magical? All it really boils down to is a really long stick that when one end moves, the other ends moves as well.

And no, not FTL travel. But the transmission of information at FTL speeds.

Yes, your stick is that magical. Ain't no such thing as a (literally) solid body. It's a bunch of atoms held together by the electromagnetic force. That force is of finite strength and it travels at the speed of light. (Who would have guessed?) If you hit one end of the rod with a hammer, the rod gets slightly compressed and that compression travels with the speed of sound, a tiny fraction of the speed of light. Your stick would be dammed heavy, too, even if was made of hydrogen. 

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42 minutes ago, A True Kaniggit said:

And that is what I want to know. Do the current laws of physics rule out a material that can be built into a pole that is more than a light year long.

No.  Theoretically possible, but well beyond current capabilities.  (I'll note you wouldn't need a pole a light year long for this hypothetical experiment.  If your pole was .25light years long, and the signal traveled from one end to the other in less that .25years, there's your signal FLT.  With current technology we could perform this experiment using a pole 1km long (or shorter).  The problem is the next question.

Quote

And do they state that this pole can't be so perfect in form that when pushed at one end, the other end moves simultaneously?

In short, yes, they do state this.

It's not about perfection of form.  It's about the interaction of the fundamental forces (in this case electromagnetism).  Force is carried by a particle (boson), which also adheres to the laws of physics, and thus can't travel faster than the speed of light.  When one object of matter pushes another, the electromagnetic interaction between individual atoms (i.e. the bosons) carries the force of the push.  You're getting into deep physics here, but your question has been asked before, so maybe this link will help with the explanation.

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39 minutes ago, A True Kaniggit said:

And that is what I want to know. Do the current laws of physics rule out a material that can be built into a pole that is more than a light year long. And do they state that this pole can't be so perfect in form that when pushed at one end, the other end moves simultaneously?

I think building a pole that long would be theoretically possible, although fantastically difficult because any gravitational forces would cause it to break apart.

Building the pole so perfectly that when pushed at one end, the other end moves simultaneously is indeed impossible. 

EDIT:  Ded as Ned beat me to it with a better answer.  B)

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Thank you everybody. I've finally been convinced that under the current laws of physics, though it may be possible to build a really long pole, science says it wouldn't allow us to transfer information FTL. I appreciate the responses.

 

 

You win again Albert.

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3 hours ago, A True Kaniggit said:

And I would agree. In this scenario nothing physically is moving faster than the speed of light. However information would be delivered faster than the speed of light itself could transmit it.

The material you postulate doesn't exist and you have no idea if there could be enough energy to make such material move.  You might as well say, "if magic exists we can create FTL communication."

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9 hours ago, Pebble said:

So I guess if you could somehow pre-compress all the atoms and keep them permanently compressed, it might just be possible.

The problem is that if you compress them too much, you get nuclear fusion (and if you don't compress them too much, they can be compressed more so the rod isn't impossible to deform). Even if you somehow had enough energy to create it, and assuming there's enough matter in the universe, a single atomic nucleus a light year long would be... quite a long way up the periodic table. Elements tend to get more unstable the higher up they are, so this new element would probably not have the properties we'd want in a rod. Also, it would probably be a black hole, which would present additional difficulties in pushing on one end, and in determining whether or not the bell rang at the other end.

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6 hours ago, felice said:

Even if you somehow had enough energy to create it, and assuming there's enough matter in the universe, a single atomic nucleus a light year long would be... quite a long way up the periodic table.

It would not help with FTL communication even if there was such a thing. Nuclei are held together by the strong nuclear force (which is only effective over extremely short distances, but never mind) the force carrier of which is the gluon, a massless particle which, like all massless particles, moves at the speed of light.

More generally, the idea of the speed of light as a cosmic speed limit is really robust. There are many tricks attempting to cheat it, but all are flawed in one way or another (even the quantum entanglement ones). There are potential loopholes based on general relativity (e.g. the Alcubierre drive, traversable wormholes, Krasnikov tubes, etc.), but we have not found a way to exploit them yet as every one of them requires negative mass or energy. This is not as impossible as it sounds: there are quantum effects which resemble it (the most famous of which is the Casimir effect). Unfortunately, the quantum effects we can experimentally achieve are tiny and the ones which we need are astronomically large.

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5 hours ago, Altherion said:

It would not help with FTL communication even if there was such a thing. Nuclei are held together by the strong nuclear force (which is only effective over extremely short distances, but never mind) the force carrier of which is the gluon, a massless particle which, like all massless particles, moves at the speed of light.

More generally, the idea of the speed of light as a cosmic speed limit is really robust. There are many tricks attempting to cheat it, but all are flawed in one way or another (even the quantum entanglement ones). There are potential loopholes based on general relativity (e.g. the Alcubierre drive, traversable wormholes, Krasnikov tubes, etc.), but we have not found a way to exploit them yet as every one of them requires negative mass or energy. This is not as impossible as it sounds: there are quantum effects which resemble it (the most famous of which is the Casimir effect). Unfortunately, the quantum effects we can experimentally achieve are tiny and the ones which we need are astronomically large.

Doesn't Quantum Entanglement hit at the very idea of "locality" which means distance may be an illusion in the first place thus meaning the speed of light doesn't matter because distance is illusory?

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