Why is "now" the same for everybody?

[tar]

Seems to me, there must be a reason why everything on Earth and Everybody on Earth, exists in the same now, and the rest of the universe seems to exist immediately, but we know it's actual now will not "get here" 'til another later time, depending on the distance and the relative velocity of an event.

 

Somewhere I read that a human "present moment" is about 2 and a half to 3 seconds long. Perhaps that has something to do with the round trip time of various sensory inputs plus predictive motor simulations plus motor impulses, plus the sensory inputs of the results. And we are always "in the middle" of this process. But perhaps as well, since we are used to this "lengthy" present moment, we can easily concieve of everywhere that light can get and back, in 2 and half to three seconds, as "here and now". That's about half a million miles, or a sphere around wherever we sit, a million miles in diameter. Certainly includes everybody else on Earth, and the moon (238 thousand miles or about a moment away...456 thousand mile round trip for light), but little else is "inside" our moment.

 

In the fall, I hear we are to attempt a remote, "piloted" landing of a craft on Mars. On the way now, I hear. The pilot is going to have to stretch his or her "moment" quite a bit. Mars varies from half an AU (four minutes or 80 moments to 2 and half AU or 400 moments, depending on whether its behind us or on the other side of the Sun). I believe the landing is going to happen about 17 minutes away or about 340 moments to get a signal there, and 340 more moments to get a signal back. In anycase the pilot is bound to have a bit of trouble imagining what the craft is doing "now". I would think, anyway.

 

How about you? What do you think?

 

Regards, TAR

 

How is that going to work, anyway. If the pilot sees with his camera, that the craft will hit an obstacle on its present course, in a minute, the craft already hit the obstacle 16 minutes ago??

[Spyman]

How is that going to work, anyway. If the pilot sees with his camera, that the craft will hit an obstacle on its present course, in a minute, the craft already hit the obstacle 16 minutes ago??

There is no pilot in 'direct' control, the Curiosity rover will have an fully automated landing at Mars on the night of the fifth of August.

 

Huge Mars Rover's Landing Will Be '7 Minutes of Terror'

"We've got literally seven minutes to go from the top of the atmosphere to the surface of Mars, going from 13,000 miles per hour to zero in perfect sequence, perfect choreography, perfect timing," Rivellini added. "And the computer has to do it all by itself, with no help from the ground. If any one thing doesn't work just right, it's game over."

http://www.space.com/16296-curiosity-mars-rover-landing-terror.html

[tar]

Spyman,

 

Well thanks for that. Guess I should have read about it, before jumping to conclusions. I had thought it would "have to be" automated, and was perplexed at the thought that anybody could have direct control of the craft.

 

Still leaves the OP question however, as in whether or not the Curiosity has left our now. Or whether the Curiousity will expand our here and now to include Mars, and expand our moment from 3 seconds to a half hour, and expand our "here" from the orbit of the Moon, to the orbit of Mars (including the Sun, in our here and now).

 

Regards, TAR2

 

Or have we created AI, that can exist/survive in its own here and now, on it own.

[D H]

Or have we created AI, that can exist/survive in its own here and now, on it own.

The Mars entry software is "just" control theory. You might need a masters degree or more to understand it, but it's not "AI"¹. It's just math and physics, sensors and effectors. Guidance system software indicates where the spacecraft should be based on a pre-planned trajectory and navigated state. That navigated state comes from the navigation system software, which indicates where the spacecraft is based on sensor readings and prior navigated state. The navigated and guidance state are never quite in agreement. Getting the two into alignment is the job of the control system software.

 

 

¹Is this AI? The AI community doesn't think so because it doesn't use techniques invented by the AI community. The guidance, navigation, and controls community however says what's the difference? It's not as if those techniques developed by the AI community are "intelligent". All AI techniques to date are "soft AI" (as opposed to "hard AI"). In the minds of the guidance, navigation, and controls community, those soft AI techniques are just math and physics, sensors and effectors, but just done badly.

[StringJunky]

DH

 

IIRC I think you are conversant in flight navigation systems....is it AI to you?

[tar]

There is no pilot in 'direct' control, the Curiosity rover will have an fully automated landing at Mars on the night of the fifth of August.

 

Huge Mars Rover's Landing Will Be '7 Minutes of Terror'

"We've got literally seven minutes to go from the top of the atmosphere to the surface of Mars, going from 13,000 miles per hour to zero in perfect sequence, perfect choreography, perfect timing," Rivellini added. "And the computer has to do it all by itself, with no help from the ground. If any one thing doesn't work just right, it's game over."

http://www.space.com/16296-curiosity-mars-rover-landing-terror.html

 

 

Interesting, 7 minutes of terror for who? Those who know the project will know the craft is actually currently on the surface (intact or in pieces) and has been for a while, as soon as the signals come in that the craft is ready to hit the atmosphere of Mars. I would think the terror could realistically begin seventeen minutes before its about to enter the atmosphere (going by signal reception). So why don't we expect about 45 minutes of terror? From the time "we think" the craft is hitting the atmosphere, to the time we know the rover is on the ground, intact and operational?

 

And I think the question of what or who's now we are going by, is still a good one. The universal now, though real in retrospect, is more conceptual than actual. Our actual now, concerning the entire universe, is the one that is composed of events everywhere, arriving here, now, informing us of their existence.

 

Is it just me that finds this an interesting question? Or does everybody else either have it figured out already, or not see it as a thing that requires figuring out?

 

Regards, TAR2

[Moontanman]

Well lets just hope it wasn't programmed in feet and measured in meters....

[D H]

Interesting, 7 minutes of terror for who?

It is obviously seven minutes of terror for the humans watching remotely from mission control in Pasadena, California. Entry, descent, and landing is a hand wringing time. Not quite so obviously, it is also seven minutes of terror for the humans who designed and built the Mars Science Laboratory entry, descent, and landing systems. Those systems have to be fully autonomous.

[mississippichem]

It is obviously seven minutes of terror for the humans watching remotely from mission control in Pasadena, California. Entry, descent, and landing is a hand wringing time. Not quite so obviously, it is also seven minutes of terror for the humans who designed and built the Mars Science Laboratory entry, descent, and landing systems. Those systems have to be fully autonomous.

 

It's not seven minutes of terror for the hypothetical Martians who will observe a terrifying Earth craft whizzing down from orbit to drop off a robot?

[Greg H.]

It's not seven minutes of terror for the hypothetical Martians who will observe a terrifying Earth craft whizzing down from orbit to drop off a robot?

 

They can call NASA if they feel the need to lodge a complaint.

[iNow]

The universal now, though real in retrospect, is more conceptual than actual. Our actual now, concerning the entire universe, is the one that is composed of events everywhere, arriving here, now, informing us of their existence.

I don't think it's real, at all. You seem to be trying to impose a universal frame of reference, and there quite simply is no such thing. Only on very local scales can you state that some "now" or present moment is being shared, and even then you can only say so with very limited accuracy.

 

Recall that even when you describe some slice of time as "now," you must do so from a very specific reference frame... from yours, or from mine, or from the reference frame of an astronaut on Pluto, or even from the reference frame of some distant galaxy or supercluster of galaxies billions of light years away. Once you account for the reality that these present moments are specific to a certain reference frame, you introduce the requirement to account for different lengths and times via relativity.

 

Said another way, these moments in time... these "nows" are always relative to something... some other "now" or some other point along the arrow of time, and that's true whether we're describing yours or mine or someone else's... My now and your now are neither shared nor universal, and this issue of "now" being relative to the observer is further magnified when you begin to incorporate the different perceptual processes and reaction times and delays within each of our own individual nervous systems that tie to the perception of the present moment.

[tar]

D H,

 

I knew what the 7 minutes of terror was referring to. That time span from when we knew the craft was hitting the atmosphere to when it landed. And along with the team in Pasadena, will be the rest of us, who care.

 

My suggestion is in opposition to Inow's statement, that I can not construct a universal now, or that we all don't have the ability to do such. When we say the light from the Sun takes eight minutes to get here, we differenciate between the photons hitting our eyes now, and those that will be hitting our eyes in eight minutes. The later are "just now" being released by the Sun. Inorder to have this conception, we must hold an image of two different reference frames. One where the Earth, or our individual point of focus is NOW, and one where our current reception of photons from the Sun AND the release of a different set of photons(that will arrive in 8 minutes) are occurring simultaneously. The fact that there is no "real" observer, that can experience both events at the same time, does not prevent the true conception that there are photons leaving the Sun "now" that will arrive here in 8 minutes. And they are a different set of real photons, than the set that is arriving here now.

 

If the Curiostity touches Mar's atmosphere at 5:32 EST, and it takes a signal orignating at the craft 14 minutes to reach Earth, then we will get the signal at 5:46 EST. If we are to go by when the craft "really" entered the atmosphere.

 

If we are going by when we "see" the craft enter the atmosphere, and clocking THAT event as happening at 5:32 EST (when the team sees it and starts their 7 minutes of terror), the craft would have, in actuality entered the atmosphere 14 minutes earlier, at 4:18 EST. (and has at the point we recieve the images, already landed safely, or crashed). The craft however is only existing at one place and time, at a time. In Inow's description, what time is it here, when the craft enters the atmosphere there? And if there is 14 minutes lag between what happens here, and what happens there, don't we have to chose to consider two different versions of now. One that is defined by the speed of light, and one "universal" now, that ignores the speed of light completely, and sees both events at "the same time"?

 

Regards, TAR2

 

Since I was a boy, people have been telling me that stars are so far away, that we see what they looked like a hundred or a thousand or a million years ago, and they are really existing now in another later looking state, or could even have exploded and are now gone. In order to know this thing, which is evidently true, I have to hold a "false" image of what really is, and hold a "true" image of what really isn't. Since it is both true that I see what I see, now, and it is true that I will see what really is now, later, I need to hold two different models of the same thing, one real image, and how that correlates to the real thing. What it looks like from here and now, and what it must be, in reality to look like that.

THIS here and now, to be the reference frame to which to correlate everything else. With the knowledge that the Sun really is putting out photons now that will not be the ones I see for another 8 minutes.

 

For instance, if we were to find a way to entangle two particles and keep the one, and send the other with a craft, arranged in such a manner as it would cause a light to flash on Mars when we changed the state of its partner here on Earth. We would see the flash 14 minutes after we affected the partner here. If on the other hand, we sent a signal to flash the light, we would see the flash 28 minutes later. Mar's now is 14 minutes away from ours. And an event happening simultaneously on Earth and Mars puts us both in the same "universal" now, that doesn't care about the speed of light.

Edited July 28, 2012 by tar

[D H]

My suggestion is in opposition to Inow's statement, that I can not construct a universal now, or that we all don't have the ability to do such.

iNow is correct. You cannot construct a universal "now". Simultaneity is relative.

[iNow]

It's not quite the same as learning how to do the math itself, but if you've got ~50 minutes, TAR, watching this might help a little:

 

 

http://www.youtube.com/watch?v=M7060RTp92A

 

 

Of special note are the scenes ~13m in, but even more relevant to this particular question is at time point ~19m in the video (the whole thing is quite worth the watch, though).

[tar]

Inow,

 

Interesting, but not very satisfying. There are concepts tossed around, willy nilly, with inconsistencies shrugged off, with "well it could be this or that" or "we don't know why". And impossible things allowed, just to prove a side point.

 

For instance, the guy goes off with his tickets to the future, orbits a black hole for a while, comes back "only having aged a few hours" and the ticket counter gal, is now an older woman...

 

What black hole do you know, that he could have reached, inorder to orbit, in an hour? He would have to age a few hundred thousand years, just to GET TO a black hole.

 

And you say, I cannot construct an imaginary now, yet they sliced the universe into "now" slices and manipulated them, according to a bike rider's motion...inorder to show I can't have a now slice, in the first place?

 

And IF all the times and places of the universe, near and far, past and future exist, on equal footing, what possible sense could a statement like "the universe is currently accelerating" possible make?

 

My point, or question in the OP still stands. We all, here on Earth agree we are in THIS cycle of the Earth around the Sun, even though it has circled the Sun 4 billion times before, and there will be future cycles. We all agree on the day, the hour, the minute, and thanks to the cesium clock in colorado, we all "are in" the same, well defined and measured second.

There is no thing, or person on Earth, that is currently in a previous cycle, or a later one. We are all together, in concert, consistently in THIS cycle. Seems to me, there must be reasons for this. Seems to me the reasons are real and important.

 

We are all in the same now, here on Earth, which means something. AND we consider the WHOLE universe is 14.3 billion years old. All of it. Each and every particle in it...considered to be experiencing THIS moment in the life of the universe.

 

And you say I can't construct a universal now? How come then scientists can say it is a certain age, if all of it, is not the same age, at once. And that once, that moment, is NOW?

 

Regards, TAR2

[D H]

Interesting, but not very satisfying. There are concepts tossed around, willy nilly, with inconsistencies shrugged off, with "well it could be this or that" or "we don't know why". And impossible things allowed, just to prove a side point.

What inconsistencies? Other than the fact that relativity is not consistent with Newtonian mechanics, there are no inconsistencies that we know of. With regard to that inconsistency with Newtonian mechanics: It's Newtonian mechanics that is wrong. Demonstrably wrong.

 

As far as concepts tossed around, willy nilly, well this is a video narated mostly by Brian Greene. I'm not a big fan of him, or of Brian Cox, or of Michio Kaku. In my opinion, all three do a big disservice to science by spending a whole lot more time mystifying physics rather than explaining it. A good science popularizer demystifies science. These three do not do this.

 

 

For instance, the guy goes off with his tickets to the future, orbits a black hole for a while, comes back "only having aged a few hours" and the ticket counter gal, is now an older woman...

That's the general relativistic version of the twin paradox. It is demonstrably correct. You don't need a black hole. All you need is a somewhat large body such as the Earth. Take an atomic clock up a mountain and it will run faster; see http://www.wired.com/science/discoveries/news/2007/12/time_hackers/?currentPage=all. Put an atomic clock on an airplane and fly it around the world. The clock will run faster or slower than a ground-based clock depending on whether the plane flies east or west. This is the Hafele–Keating experiment; see http://en.wikipedia.org/wiki/Hafele–Keating_experiment. If you have a GPS receiver, it wouldn't work if the universe behaved in the Newtonian manner you erroneously insist on thinking the universe behaves.

 

 

My point, or question in the OP still stands.

No, it doesn't. It is demonstrably false. It happens to be approximately correct on the surface of the Earth because clocks at rest anywhere on the surface of the Earth will tick at nearly the same rate. The gravitational time dilation from the tallest village in Tibet or the Andes to the Dead Sea is only measurable by atomic clock. Just because it is approximately correct on the Earth does not mean it is universal. It isn't.

[iNow]

We all agree on the day, the hour, the minute, and thanks to the cesium clock in colorado, we all "are in" the same, well defined and measured second.

Actually, no. We are not.

 

We are all in the same now, here on Earth, which means something.

Again, I know it's quite counter intuitive, but unfortunately this is simply not true, despite what your gut feelings and initial perceptions may suggest... We are not all in the same "now." You can of course choose to continue ignoring this fact if you'd like, but it is quite demonstrably true.

 

---

As far as concepts tossed around, willy nilly, well this is a video narated mostly by Brian Greene. I'm not a big fan of him, or of Brian Cox, or of Michio Kaku. In my opinion, all three do a big disservice to science by spending a whole lot more time mystifying physics rather than explaining it. A good science popularizer demystifies science. These three do not do this.

The Nova program on PBS does much better than most, and is quite a solid show overall, but I do tend to agree completely with you regarding these popularizers and the way they thrive on mystery instead of demystification. However, to me that video seemed like the quickest and easiest way to convey this point to TAR without him having to go through several semesters of calculus and relativity courses.

[Moontanman]

It's not seven minutes of terror for the hypothetical Martians who will observe a terrifying Earth craft whizzing down from orbit to drop off a robot?

 

 

It would be terror if the Martians knew humans....What was it an old Indian told one of our lunar astronauts when he was asked if he had a message for any moon people, he said "don't trust these guys they'll steal your land...

[tar]

Actually, no. We are not.

 

 

Again, I know it's quite counter intuitive, but unfortunately this is simply not true, despite what your gut feelings and initial perceptions may suggest... We are not all in the same "now." You can of course choose to continue ignoring this fact if you'd like, but it is quite demonstrably true.

 

---

 

The Nova program on PBS does much better than most, and is quite a solid show overall, but I do tend to agree completely with you regarding these popularizers and the way they thrive on mystery instead of demystification. However, to me that video seemed like the quickest and easiest way to convey this point to TAR without him having to go through several semesters of calculus and relativity courses.

 

Inow,

 

I am trying to not ignore anything. It is obvious to me that my now is separate from other nows in some senses and the same in others. In some ways the future has already occurred, in at least the general sense, that any and all photons that are entering the Earth's atmosphere from other stars now, were necessarily "on their way here" yesterday. They could not arrive here today, coming from "there" unless they traversed the space between this here, and that here. And it took some time for them to make the trip. Thus they had to have left the other here, the other star I am considering, at an "earlier" time than now. That is, that particular set of photons, arriving here today from an object 10 light years distant, left that object "at the same time" that the Earth was engaged in cycling the Sun, 10 cycles of the Sun ago. For this to be true, and because this is true and actual, it requires that there is another set of photons, being released from that distant object during this cycle of the Earth around the Sun, that will arrive here during the period of time that the Earth is in its 10th cycle of the Sun, from now. And there is a steady stream of photons, coming from that distant object that will arrive here in all the moments between now and 10 years from now, that are already, actually in existence in the universe, in that space between the distant object and Earth. New ones leaving "just now" in that "universal" now, that we can concieve actually exists, in reality, understood only from a "God's eye view", that is not bound by the speed of light, but can be known to be true and real, non-the-less.

 

I never quite understand, when people are assuming this God like understanding of "now" in a correct and true and real and scientifically accurate manner, and when they are "misunderstanding" the nature of this universal now. Or when indeed, I am misunderstanding what our measurements and logic have to say about it. Where I am "making my mistake" in characterising the nature of time and space.

 

I understand that time is relative. In many senses. But there are certain assumptions, or starting points, it seems one has to have, inorder to say anthing about it at all. I am considering that the best starting point is here and now, and that is the real and measurable moment we all have access to. And from here and now, we can figure by the evidence, how the rest of the universe must be configured. With nothing really making any sense at all, if we can't at least start with our basic intuition and common sense.

 

Time and space and the reality of it, what ACTUALLY is occuring, considering all the entities and energies, and cycles within it, will not change much, whether I understand calculus or relativity, or not. The calculus is derived from the things that are occurring, and are based on our concepts and judgements about the things that are occurring. While there many be many points of reference, and many ways to look at it, I don't find much value in attempting to look at it, from a reference point that DOESN'T exist. Seems more sensible to attempt to explain it, from here and now.

 

Regards, TAR2

[iNow]

That is, that particular set of photons, arriving here today from an object 10 light years distant, left that object "at the same time" that the Earth was engaged in cycling the Sun, 10 cycles of the Sun ago.

At "the same time" relative to what or whom?

 

New ones leaving "just now"...

"Just now" relative to what or whom?

 

... in that "universal" now,

There is no such thing, though.

 

I understand that time is relative.

I know you may think this is true topically, and I know from a cerebral point you recognize it would be folly to argue otherwise, but I really don't think you do "understand that time is relative" given the way you've framed your response. You may understand that people say this, but I am unsure you understand what it truly means. To be fair to you, I also struggle with this from time to time, but I've learned when my own personal intuition and common sense view needs to be discarded for failure to accurately represent the reality around me.

 

I am considering that the best starting point is here and now, and that is the real and measurable moment we all have access to.

Regardless of how many times you continue to assert the contrary, there is no such universal starting point, and that "here and now" is quite specific to you and you alone.

 

With nothing really making any sense at all, if we can't at least start with our basic intuition and common sense.

Your common sense and intuition need to be abandoned in this discussion. They will only continue to lead you farther and farther astray from the truth.

[tar]

Just an aside: The atomic clocks that were used in the experiment where certain of the clocks were flown East and certain West and compared upon return. Where are those clocks now? Are they still operational? Has their history been tracked between then and now, in terms of their positions and relative velocities? I was just wondering if the descrepacies in their counts of cycles have become greater (indicating some physical differences in the clocks), remained the same (fortifying the notion that the descrepencies were solely caused by their relative motion and positions in our gravational field), or whether the descrepencies have reduced (indicating that there might be some "normalizing" factors that cause slow clocks to catch up, and fast clocks, to fall back into the pack). I raise this question, considering the thought that the universe is considered to be the same age, everywhere. If this is to be the case, certain portions of the universe, should not be able to get much older than others (have their clocks move faster) and others age much less than others (have their clocks tick slower), indefinitly, with no forces and principles acting to pull the errant clocks, back into sync with the rest of the universe.

Edited July 29, 2012 by tar

[absolutely]

if now is the same then now is to truth and not to time, since there cant b plural objective right perspective, objective true reality is one

 

 

that is why time concern pass and future only so never the present, and why past is the future as the beginning starts from its end, and futur is the past since what would become real is what was a sense

 

so it is like past and futur realize the concept of time in truth pointing relativism of infinite truth in abstract absolute terms that never exist

 

 

while the concept of present is all to true existence from what is known definitely about truth being truly present always free as a constant fact the epsilon is truth presence which is absolute freedom fact which exist

 

 

 

it is illogical to consider that an objective fact that could b perceived, could b a reason of free perception sense while the fact itself is not free of its own presence

 

 

i hope that u dont see my ways of speaking ugly like others sites where i am banned from bc of my free thoughts or style of writings

[D H]

I raise this question, considering the thought that the universe is considered to be the same age, everywhere. If this is to be the case, ...

It isn't the case, so everything that follows is wrong. You are implicitly assuming that clocks everywhere tick at the same rate. They don't.

 

When cosmologists say that the universe is 13.75 billion years old, they are referring to a clock that is well-removed from any small scale variations in density such as planets, stars, black holes, and galaxies, and is locally at rest with respect to the cosmic microwave background radiation.

 

 

---

 

i hope that u dont see my ways of speaking ugly like others sites where i am banned from bc of my free thoughts or style of writings

I do see your way of writing as ugly. I also see it as a sign of laziness, arrogance, and stupidity. It's lazy in that you clearly can't bother taking the time to spell out words, write proper sentences, or express your thoughts clearly. It's arrogant because your writing gives the impression that you think your time is worth so much more than that of those who read your rot. It's a sign of stupidity because the ability to express oneself clearly is a key indicator of intelligence.

 

If you aren't lazy, arrogant, and stupid, show it. Please take the time to avoid text speech, write proper sentences, and communicate clearly. If you are lazy, arrogant, and stupid, why should I waste my time responding to you?

[absolutely]

judging a person by its way of writing just bc it looks ugly to u, show and reveal ur own standard that according to my knowledge or judgment should never exist

 

 

 

u exhibit clearly ur pride of being only one, as if it is an absolute right to consider then any and all according to ur positive will as existing one

 

 

 

mister u should not b allowed to write, words are based on conceptions abstractions so exponential of levels height that include everyone and thing freedom as plural ones realities free and without limiting its objective perspective and facts recognitions to any

 

 

insisting to call smthg negative from pointing it by subjective qualifications that mean nothing real, is in truth stating that the thing do not exist and only u is there

 

while in fact u r clearly using pervert ways that u belong to, in meaning to affect the perception of others to that thing, so dreaming about a kind of control u can get of others minds by possessing smthg they see

[Phi for All]

judging a person by its way of writing just bc it looks ugly to u, show and reveal ur own standard that according to my knowledge or judgment should never exist

 

 

 

u exhibit clearly ur pride of being only one, as if it is an absolute right to consider then any and all according to ur positive will as existing one

 

 

 

mister u should not b allowed to write, words are based on conceptions abstractions so exponential of levels height that include everyone and thing freedom as plural ones realities free and without limiting its objective perspective and facts recognitions to any

 

 

insisting to call smthg negative from pointing it by subjective qualifications that mean nothing real, is in truth stating that the thing do not exist and only u is there

 

while in fact u r clearly using pervert ways that u belong to, in meaning to affect the perception of others to that thing, so dreaming about a kind of control u can get of others minds by possessing smthg they see

!

Moderator Note

absolutely, you are breaking our rules about clear communication and etiquette. Please re-read the rules and keep your posts civil and understandable, or you risk suspension or banishment.

 

If you have a problem with this modnote, please report the post using the Report Post function. Do NOT further derail this thread by replying to the modnote here.