from the how-long-is-forever?-Sometimes-just-one-second dept.
Arthur T Knackerbracket has processed the following story:
How do we know that time exists?
The alarm goes off in the morning. You catch your morning train to the office. You take a lunch break. You catch your evening train back. You go for an hour’s run. Eat dinner. Go to bed. Repeat. Birthdays are celebrated, anniversaries chronicled, deaths commemorated. New countries are born, empires rise and fall.
The whole of human existence is bound to the passage of time. However, we can’t see it and we can’t touch it. So, how do we know that it’s really there?
“In physics, we have what we call the idea of ‘absolute time’ and it’s used to describe different changes as a sequence of events,” Koyama begins. “We use Newtonian physics to describe how things move, and time is an essential element of this.” Koyama is a Professor of Cosmology in the Institute of Cosmology and Gravitation at the University of Portsmouth.
To this day, classic Newtonian thought on time – where time is constant throughout the universe – is still a good approximation of how humans experience time in their daily lives. We all experience time in the same way and we all synchronize our clocks in the same way, no matter where we are in the world, whether that be London, Tokyo, New York, or Buenos Aires.
Physicists though have discovered that time can actually behave differently and is not as consistent as Newton thought.
“When we speak of time, we need to think of space as well – they come in a package together,” Koyama says. “We cannot disconnect the two, and the way that an object moves through space determines how it experiences time.”
In short, the time you experience depends on your velocity through space as the observer. This works as outlined through Einstein’s special relativity, a theory of how speed impacts mass, time, and space. Additionally, according to Einstein’s general theory of relativity, the gravity of a massive object can impact how quickly time passes. Many experiments have been undertaken that have since proven this to be true.
Physicists have even found that black holes warp the immediate space-time around them due to their immense gravitational fields. Supported by the European Research Council, Koyama continues to investigate this theory.
“A good, solid example to get your head around all of this is to look at how we use GPS,” Koyama continues. “GPS works due to a network of satellites orbiting the Earth. They’re placed at a very high altitude and thus the gravity they experience is weaker. Therefore, time should actually go faster for them than it does for us on the ground, where we experience higher gravity. But because the satellites are traveling at very high speeds around the planet, this in effect helps to slow time down, compensating for the lack of gravity.”
Understanding how these two effects work and influence each other is essential for ensuring that the global GPS network functions correctly. And a crucial ingredient in this is a consistent theory of time that explains how objects move. So clocks aren’t telling us falsehoods: time indeed exists outside of our own perception.
Finally, the question of whether time travel could one day be possible had to be put before Koyama. As a professor of cosmology at the University of Portsmouth, he is best placed to tell us the truth.
“I’m sorry to disappoint you but for time travel to be possible, we would need to discover a completely new type of matter that has the power to change the curvature of time and space,” Koyama says. “Such matter would require properties that simply do not exist in nature. We physicists strongly believe that going back to the past is simply impossible – but it’s nice to fantasize about it.”
(Score: 3, Interesting) by RedGreen on Wednesday August 24 2022, @11:50AM
Who cares what we define and agree to as time is followed by all of us, at least I have not heard from any of the massive amount of contrarian morons amongst us disagree with the concept. That is all that matters for it to exist we could call it any other damn thing you want, say the passage of gooblegook for all it matters. We humans at least in the world that has clocks seem to mark the passage of what is called time universally, for tribes still living in the forest untouched by our parasite civilizations, no clue what they do with the idea..
"I modded down, down, down, and the flames went higher." -- Sven Olsen
(Score: 2) by PiMuNu on Wednesday August 24 2022, @12:32PM (3 children)
It might be worth saying that physics describes the physical world, outside of consciousness, pretty well, except for quantum mechanics.
In quantum mechanics the whole concept of "wave function collapse" is ill-defined; it relies on some assumed separation of the observer from the observed system. That isn't really valid - the brain is a quantum system so one must treat the interaction of the brain with the observed system as part of the problem.
Interesting article here:
https://arxiv.org/pdf/quant-ph/0509042 [arxiv.org]
(Score: 3, Interesting) by PiMuNu on Wednesday August 24 2022, @12:33PM
ps: and to relate it back to TFA, (physical) time appears as a variable in e.g. Schrodinger's equation, which one may relate to experienced time via the interaction of the world with the brain via "wave function collapse"
(Score: 5, Informative) by maxwell demon on Wednesday August 24 2022, @01:57PM
For arXiv, please always link to the abstract page. In this case: https://arxiv.org/abs/quant-ph/0509042 [arxiv.org]
From the abstract page, the text is merely one link away, but from the pdf, there's no way to the abstract page except for URL editing. And the abstract page contains important information that's not usually found in the actual paper.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by hendrikboom on Wednesday August 24 2022, @08:54PM
Another way of looking at it is that the observer (a quantum system) becomes correlated with the observed (another quantum system).
(Score: 3, Insightful) by maxwell demon on Wednesday August 24 2022, @01:35PM (3 children)
Most of the summary seems to describe properties of General Relativity, which was news in 1915, but certainly not now. Of course, there are still unknown things in GR, and therefore ongoing research. The summary also says that someone named Koyama does research in that field, which isn't that special either; lots of people do that. If he has found something newsworthy, the summary certainly fails to tell us that, let alone what he found.
The summary also cannot count as introduction to GR, as for that it's not concrete enough, even for a popular science treatment.
So what exactly is this summary trying to tell us?
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by jonathan on Wednesday August 24 2022, @04:45PM (1 child)
Thank you. I was looking at this from a laymen's perspective and was thinking it sounded a lot like timey-wimey gobbley goop.
I was also recalling a phrase from The Real Ghostbusters tv show where Ray had said 'Remember, time is what keeps everything from happening all at once.'
It speaks volumes that a cartoon show has a better answer in one sentence than this article does.
The episode is "Play Them Ragtime Boos" in case anyone cares.
(Score: 2) by crafoo on Wednesday August 24 2022, @04:55PM
https://en.wikipedia.org/wiki/Loop_quantum_gravity [wikipedia.org]
loop quantum gravity is interesting. essentially uses quantized space-time to eliminate singularities (center of black holes), but are just "really really massive".
not a theory yet. as as far as I know, no one has thought up a way to test it. so it's just more "almost science", or "theoretical science", or "brain farts" depending on who you ask.
(Score: 0, Spam) by Santarchus on Friday August 26 2022, @06:18PM
If not for Maxwell's Demon, discussions of metaphysics on SN would take forever to go nowhere.
aristarchus
(Score: 3, Informative) by oumuamua on Wednesday August 24 2022, @02:12PM
It's complicated and PBS Space Time nicely breaks it down for you: https://www.youtube.com/watch?v=msVuCEs8Ydo&t=632s [youtube.com]
https://www.youtube.com/watch?v=YycAzdtUIko [youtube.com]
https://www.youtube.com/watch?v=EagNUvNfsUI [youtube.com]
Even so, only physics majors are likely to understand it.
(Score: 2) by Opportunist on Wednesday August 24 2022, @04:02PM (2 children)
Time is just natures way to avoid having to deal with too many things happening simultanously.
(Score: 2) by Thexalon on Wednesday August 24 2022, @05:50PM
"Time is an illusion. Lunchtime doubly so."
The only thing that stops a bad guy with a compiler is a good guy with a compiler.
(Score: 2) by aafcac on Wednesday August 24 2022, @09:12PM
I've thought for a while that time is tied into entropy, as entropy also generally moves in the same direction as time does, and you can't really move backwards in either case. Not that this is a particularly original thought.
(Score: 2) by istartedi on Wednesday August 24 2022, @04:58PM
If my whole world were a dream, it would be as real to me as it is unknown to you.
Collectively we experience time, so it's real to us. It might not be real from outside the Universe. We can't inquire outside the Universe any more than a dreamer can inquire outside of sleep without waking up.
Wake-a-tronic drive is online. Engage!
Appended to the end of comments you post. Max: 120 chars.
(Score: 2) by legont on Wednesday August 24 2022, @11:23PM
What exactly is my velocity through space? How about yours?
"Wealth is the relentless enemy of understanding" - John Kenneth Galbraith.
(Score: 4, Interesting) by bzipitidoo on Wednesday August 24 2022, @11:53PM (3 children)
We are entirely too enthralled with the idea of traveling back into the past. The way we talk about time lends itself to this kind of wishful thinking. Some of us rather like the idea of taking a few tools and our current knowledge of nature, and using it to impress the heck out of the ancients, perhaps for purposes of exerting dominance over them. For some, the thought of how easy that would be is very sweet. Bomb an entire army into oblivion, and clean up with a few machine guns. Swords and bows would have no chance whatsoever against Air Wolf. Basically the story of A Connecticut Yankee in King Arthur's Court.
Some other flawed terminology are "light speed" and "absolute zero". The first naturally leads to the idea of "faster than light". SF abounds with FTL. For temperature, an easy extension of the idea as expressed in that terminology is "below zero". What "absolute zero" really is, is "absolute stillness." You can't be more motionless than completely motionless, such a thought makes no sense. The problem with "light speed" is that word "speed". If we could come up with better terms for what is really going on, we wouldn't have all this dreaming of FTL.
One more example of bad terminology: "data compression". That term gives people the idea that if you just somehow squeeze harder, you can compress more. Why can't you take a zip file, and zip it again, and again, and thereby make it smaller and smaller? Keep zipping it until it has been reduced to some desired target size? Many people fall into that kind of thinking. You have a sort of vague idea that it can't be that easy, but you don't know why. What data compression really is, is redundancy removal. Call it that, and it becomes much clearer why you can't shrink it down indefinitely. Once all the redundancy is removed, you're done, the data can't be "compressed" any more, there is no more redundancy to remove.
(Score: 0) by Anonymous Coward on Thursday August 25 2022, @01:21AM (2 children)
That's crazy talk. Next you're going to tell me you can't take a CCTV security video and keep zooming in until you can read the name on the driver's license!
(Score: 1) by anubi on Thursday August 25 2022, @11:00AM (1 child)
I get the strong idea that resolution can be changed - given multiple captures if a bit of positional "noise" is added.
This used to be a common technique of increasing the resolution of digitizers. You want 16 bit resolution but it's a 12 bit ADC? Take 16 readings. Add em all together.
Anyone seen software that does this with images? That is, takes many frames of video to make one high res still?
Of course, once you've done that, nothing says you can't step through the video frame by frame to clean up the whole thing.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 1, Informative) by Anonymous Coward on Thursday August 25 2022, @05:54PM
There are two different things going on in what you suggest. The first is simply averaging down the random noise inherent in the image, which will reduce the noise by a factor of the square root of the number of frames used. Astronomers use this technique. You take a bunch of short exposure images where the atmospheric motion is frozen out, align them and add them up. There's a number of software packages out there to do that. The other effect that happens, which is what you explicitly mention, is improving the image resolution by slight positional offsets. What you're referring to here is what is known in image processing as superresolution. I'm not sure what is openly available, but something like OpenCV seems to have just about everything in it. Superresolution can give you a modest improvement in image resolution, but it can't work miracles (like on a NCIS episode).
Also see this video [youtube.com]. (I haven't watched it through myself, but it appears he goes over the basics, including showing the difference between a single shot and various numbers of multiple shots)
If you want to see it done hard core: https://www.noirlab.edu/public/news/noirlab2220/ [noirlab.edu]
That was done using 40,000 images of 60 ms exposures. It also made use of adaptive optics out of necessity due to the large size of the mirror; this wouldn't be an issue for the backyard astronomer.
(Score: 2) by jb on Thursday August 25 2022, @04:10AM
...lunchtime doubly so.