As of now, all there is is cherenkov radiation (which isn't really the same thing
):http://en.wikipedia.org/wiki/Cherenkov_radiation
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Mind. Blown. The basics of how spacetime and light work
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As of now, all there is is cherenkov radiation (which isn't really the same thing
):http://en.wikipedia.org/wiki/Cherenkov_radiation
mmazurkiewicz
Member
i don't believe most of the space theories i read about anymore. it seems that every other month something new happens and scientists come out to say that their old theory was wrong this whole time.
DiipuSurotu
Banned
In some ways there are still differences between "space" and "time", isn't there? I mean why is it that we perceive "space" as three dimensions but "time" as only one?
It's how it's reported for clicks, everything is some paradigm breaking event and we need to start over. It's incredibly damaging for science literacy because of your reaction. The reality is that level upheaval is incredibly rare. Even something like the thing in the OP, special relativity (formulated more than a century ago) which was a very different look at reality didn't completely supplant Newtonian or classical mechanics. Science is an iterative process, new data doesn't mean everything before it is wrong.
I came to post this, more or less. The example in the OP is BS. If you're sitting at your computer, like it says in the OP, you're not traveling-through-time-but-not-space. Our planet is constantly hurling through space. So is our solar system. Everything is.
What we have here is a gross over-simplification.
Krappadizzle
Member
Would you say you are a ..."mad scientist" right now?
I don't get people's loyalties sometimes. I love going to Reddit's NASA page. Shit is fun to look at. /shrug
Wait until human pattern recognition gives that more significance than it merits.
This theory is around a century old. And was an iteration on Newton's 'accurate enough for many cases' Theory of Gravity and Relativity.
If you travelled west at 50mph, in an hour, you'd travel 50 miles west and 0 miles north.
If you travelled north at 50mph, in an hour, you'd travel 50 miles north and 0 miles west.
If you travelled northwest at 50mph, in an hour, you'd have travelled like 37 miles west and 37 miles north(haven't done the math, just eyeballing it in my head).
So I don't understand the analogy.
The Technomancer
card-carrying scientician
That's because most of the time the analogy isn't presented with proper vector math because most people who haven't done college math don't understand vector math (I usually add a disclaimer to this effect). If you do substitute that for the simple addition example and that's actually the more valid way to view it
The important part is knowing that a vector to the northeast has components in both the north and east directions that compose the full vector
Hoho for breakfast
Member
No even if you "understand" you should still be very confused. Nobody today knows wtf this all means on a fundamental level. We don't know what time is really. Hell we don't know if what we perceive as the flow of time is actually a real thing or some human illusion. We have a way to go.
The One Who Knocks
Member
His Maths is wrong (it's a minor issue regarding the figures though) but the idea of the analogy is good. Perhaps visualizing it will help:
First instance, you travel East at 100m/s (I'm not doing it in m/h, but it really makes no difference).
Second instance, you travel North at 100m/s
third instance you travel Northeast at 100m/s.
What's the difference between all three? Well, the difference is in the components as the speed (or magnitude of the velocities) is the same each time.
In the first example, one is going 100m/s East, and 0m/s North.
In the second example, one is going 0m/s East, and 100m/s East.
In the third example, you are simultaneously traveling 100/(2^1/2) m/s in an Easterly direction and 100/(2^1/2) m/s in a Northerly direction.
EDIt; whoops, that was embarrassing, corrected the notation.
Dion Blaster
Member
I think the problem most people have trouble getting their head around is what does traveling northeast mean, practically? My understanding is that it is further behind in the flow of time relative to something that stayed at rest. I'm not sure though.
Ok, yea, the '100mph NE is the same as 50mph E and 50mph N' thing threw me off. That didn't sound right at all.
The important thing is that its ultimately the same speed and the components are equal(in a 45 degree vector, at least).
For us, with mass, we are always traveling through time. So lets say time is East. Traveling through space is North. We are always traveling East. The only way we can stop traveling East is if we were traveling straight North, but that would require being massless like light. So we cannot do that.
Sitting still, we are moving through time(or East). Whenever we move through space(N), we are still moving through time(E). So basically, from a human perspective, you are traveling NE anytime you move through space, since passing through time is essentially a given.
Yes.
We are technically moving at roughly 483,000mph through space. So sitting still from a human standpoint doesn't mean you are traveling solely through time.
But since the speed of light(c) is 670,000,000mph, it would be a rather negligible effect were you to theoretically be completely still in space. A 0.07% increase in perceived time. Or in other words, with a lifetime of 75 years on the dot, it would knock 5 days off your life.
IndoAssassin
Banned
Of course it's a gross oversimplification, but as you can see, people are on different knowledge levels and not everyone will understand every complication, simplification, analogy or brute definition.
The point is to demonstrate that your motion in time and space change relative to one another.
Yeah I was waiting for someone to do a Pythagorean example but I was just too lazy. Good job.
DiipuSurotu
Banned
Are you guys saying that light doesn't travel through time? This is a part I don't understand.
For example, the light from the sun takes about 8 minutes to reach the Earth. Surely that means that light does travel through time?
Also, why is it that time can be described as one dimension but space can be described as three dimensions?
This post makes the most sense to me, I think. So time slows upon travelling through space? How does apply to say, a spaceship travelling to another planet at high speeds? Time is slowed considerably?
1.21Gigawatts
Banned
The whole universe is in motion. I don't think you can be completely stationary.
There is no fix point for orientation and it would be impossible to avoid all the gravitational forces pulling you in different directions.
But in theory time would go by infinitely fast if you're completely stationary.
This is also helpful when thinking about what was before the big bang. Since there was no space there was no possiblilty for movement in space and therefore time went by infinitely fast. (Some say times existance is depended on space and relative velocities, so some might say time didn't even exist, but afterall whats the difference?)
And if time goes by infinitely fast there is no certain point at which the big bang happend, because infitely fast means every possible point in time is always.
That's exactly what I was describing. Assuming you would live 75 years on the dot here on Earth, being completely still in space(theoretically) would mean you died 5 days earlier.
Edit: OK I think I've got that completely wrong, assuming time scales linearly with our speed.
Don't listen to me. lol
I'm not a scientist or anything, but i like being educated on the subject. There is some good discussion happening here and i feel like there are some people who know some things.
I had a couple questions i never have a chance to ask people who would know.
If light is emitted from the edge of the event horizon of a black hole and into space, does it's wavelength get stretched as it moves outward due to the curvature of space? Could a gamma ray become an x-ray in this case?
2nd, it's my understanding that being in any gravitational field slows down time as well, and it's possible to be at rest while sitting in a gravitational field. If you aren't moving through space, and time is slowed, where is the rest of your momentum going?
I had a couple questions i never have a chance to ask people who would know.
If light is emitted from the edge of the event horizon of a black hole and into space, does it's wavelength get stretched as it moves outward due to the curvature of space? Could a gamma ray become an x-ray in this case?
2nd, it's my understanding that being in any gravitational field slows down time as well, and it's possible to be at rest while sitting in a gravitational field. If you aren't moving through space, and time is slowed, where is the rest of your momentum going?
Portugeezer
Member
Pretty much (for the people in the ship), thus things happening outside the ship will seem to happen quicker.
A video that someone linked has a good example https://www.youtube.com/watch?v=rBW2CxUCbpo&t=24m30s (video has problems playing at 480p). Also, if a planet is 1 light year away and you travel there at the speed of light (i.e. takes 1 year) you will now see the planet how it is 2 years later in just 1 year of travel.
I think the big bang was everywhere at once. Space itself was tiny, and space can move faster than light (or at least thats my limited understanding). The process is called Cosmic Inflation. The Universe is still actually expanding in all directions at once.
Question.
Two observers, A and B. A is "motionless". B is traveling to the right at 0.5c.
So B is experiencing a lot of time dilation compared to A. But from B's perspective.
Which means A is experiencing a lot of time dilation compared to B.
Who is older than the other once B stops moving?
EDIT: Actually, I guess my question implies the existence of a perspective C which can measure both their times relative to itself, if I have it right?
EDIT2: They're moving relative to each other at the same speed so neither experiences any time dilation compared to the other. Derp.
Two observers, A and B. A is "motionless". B is traveling to the right at 0.5c.
Code:
A
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B---0.5c--->So B is experiencing a lot of time dilation compared to A. But from B's perspective.
Code:
<---0.5c---A
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BWhich means A is experiencing a lot of time dilation compared to B.
Who is older than the other once B stops moving?
EDIT: Actually, I guess my question implies the existence of a perspective C which can measure both their times relative to itself, if I have it right?
EDIT2: They're moving relative to each other at the same speed so neither experiences any time dilation compared to the other. Derp.
The Technomancer
card-carrying scientician
From our perspective the light travels on time. From the light's perspective there is no time
If you could somehow reach light-speed, travel for a distance, and then slow down again, your perception would be that the journey was instantaneous. That it took you no time at all to travel the distance. This is impossible for a variety of reasons.
Well then the wormhole wouldn't be a bridge inside our own universe/to our own universe's past, would it? It would be a nexus between/connecting two different universes, the one you're entering being the reality you've set into motion by entering.
If it's different universes then there's no way for matter to travel through a wormhole since the laws of physics could be different.
The Technomancer
card-carrying scientician
Its important to be clear about what we're talking about. There might be different universes besides our own with different physical laws. This is not the same thing as there being alternate versions of our own universe with different histories or configurations. The latter is a theoretical result of some weirdness with quantum wave functions.
NobleGundam
Banned
I tried researching more about light. But couldn't find the subatomic particles that makes up photons which light is consisted of. My interest is if light does have mass but to the subatomic level.
It's probably a little off-topic but how can galaxies travel at the speed of light (or even faster??) ?. They have mass, obviously, so that doesn't make sense.
My guess would be that galaxies aren't actually moving through *space* (or moving slowly), but rather space around them is expanding. Is that correct?
My guess would be that galaxies aren't actually moving through *space* (or moving slowly), but rather space around them is expanding. Is that correct?
NobleGundam
Banned
Galaxies are moving along with space moving also.
Not if we're talking many worlds interpretation which would mean there are an infinite number of similar universes branching off for every possible quantum state. Those would have the same physics as our own because they would be nearly identical in many cases.
I'm not saying other universes can't have their own laws of physics, what I am saying is that most of the universes that branched off the same chain as ours would have identical laws.
*Everything* is 'moving' at the speed of light. Its just a matter of which dimension you're doing it in and it will be split up between both space and time. Galaxies travel through space and time just like we do.
DiipuSurotu
Banned
I think I'm beginning to understand this a bit better... but this brings to mind another question. Light's journey is instantaneous, ok, but light can't for example travel into the past, so in some way isn't it still subject to time?
I don't know maybe I'm being dumbly influenced by Interstellar but it seems to me that if something isn't affected by time then it should be "everywhen" or something.
The galaxies don't move faster than light. It is the accumulated stretching of the space in between two objects that make it look like it is going faster than light. So if two objects are close to each other, there are fewer space in between that stretches, so it seems like they go away from each other slower than comparing those objects to one much farther away.
The Technomancer
card-carrying scientician
The short answer is that its complicated. Photons are the fundamental particle of light, and they lack mass in the way that we think of it. Photons have zero rest mass, but then photons are also incapable of being at rest. But they do possess energy and mass actually is one form of energy. This has some interesting implications: for example gravity as a force is actually proportional to energy, however since the majority of the energy in all of the stuff around is is in the form of mass its essentially proportional to mass. But if you stretch out a tension spring its gravitational attraction will actually increase ever so slightly due to the potential energy it now contains.
And this is where the metaphors about "if you were traveling at the speed of light" basically start to break down and become useless. A photon's path can still be bound by two events in spacetime, its emission and its absorption. From our perspective these events occur at different times and the photon is moving in time. I could say "from the photon's perspective those events occur simultaneously" again but...well...its a photon, it doesn't have any memory with which to perceive the passage of time anyway. And if you were moving at the speed of light you might perceive the events simultaneously, but then you'd be moving at the speed of light, which is impossible. All the metaphors and what if's don't really get the reality of it across. The simplest way to put it is really just that a photon's vector in spacetime is entirely along the spatial axis, and so there is no temporal component.
*shrug*
Look up light cones if you want a better explanation of how this stuff works, although it can be a bit difficult to understand at first. Keep asking questions if you have em!
unfortunately that impression is more to do with sensationalist university publicity trying to get more clicks and funding.
as said earlier in the thread, all of our models of reality are wrong, but some are useful.
if you approach science knowing that, you don't think of it in such black and white terms of the old theory being wrong this whole time that we have to "flip the table" and start all over again. new research adds new pieces of knowledge and methods that make our models less wrong. that's how science works.
these days is much rarer to have those fundamental discoveries that completely overturn years of established scientific doctrine, but universities want to make you and the people who award grants think otherwise. *click click click* $$$
The Technomancer
card-carrying scientician
Almost all science fiction is ridiculous. That doesn't make it not valuable
I would encourage healthy amount of scepticism when reading science articles from non-scientific publications. However, the theories we are talking about in this thread were discovered by a guy named Albert Einstein a century ago, so you can probably put a little more faith into it.
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