Are Other Galaxies As Far Away As We Think They Are?

According to commonly accepted science, if I were to take off from where I'm standing at the speed of light, and head towards the Andromeda galaxy, it would take me 2.5 million years to get there.

Yet according to time dilation, the faster you go, the more time slows down. So even though it appears to everyone else that it took me 2.5 million years to get there, I would actually be much less than 2.5 million years old.

How does science reconcile this paradox? How can they say definitively that it takes light from the Andromeda galaxy 2.5 million years to get here? Wouldn't that light be much younger than we perceive it to be?

a reply to: Bone75

I thought the Doppler effect(Redshift) pretty much determined how distant the other Galaxies are from our own.

en.wikipedia.org...

a reply to: Bone75

This might interest you,

www.askamathematician.com...
I just copied and pasted the info from the link..

In order to move from one place to another always takes a little time, no matter how fast you’re traveling. But “time slows down close to the speed of light”, and indeed at the speed of light no time passes at all. So how can light get from one place to another? The short, unenlightening, somewhat irked answer is: look who’s asking.

Time genuinely doesn’t pass from the “perspective” of a photon but, like everything in relativity, the situation isn’t as simple as photons “being in stasis” until they get where they’re going. Whenever there’s a “time effect” there’s a “distance effect” as well, and in this case we find that infinite time dilation (no time for photons) goes hand in hand with infinite length contraction (there’s no distance to the destination).

The name “relativity” (as in “theory of…”) comes from the central tenet of relativity, that time, distance, velocity, even the order of events (sometimes) are relative. This takes a few moments of consideration; but when you say that something’s moving, what you really mean is that it’s moving with respect to you.

Everything has its own “coordinate frame”. Your coordinate frame is how you define where things are. If you’re on a train, plane, rickshaw, or whatever, and you have something on the seat next to you, you’d say that (in your coordinate frame) that object is stationary. In your own coordinate frame you’re never moving at all.

How zen is that?

The last coordinate to consider is time, which is just whatever your clock reads. One of the very big things that came out of Einstein’s original paper on special relativity is that not only will different perspectives disagree on where things are, and how fast they’re moving, different perspectives will also disagree on what time things happen and even how fast time is passing (following some very fixed rules).

When an object moves past you, you define its velocity by looking at how much of your distance it covers, according to your clock, and this (finally) is the answer to the question. The movement of a photon (or anything else) is defined entirely from the point of view of anything other than the photon.

One of the terribly clever things about relativity is that we can not only talk about how fast other things are moving through our notion of space, but also “how fast” they’re moving through our notion of time (how fast is their clock ticking compared to mine).

a reply to: Bone75

IMHO, there is MUCH guess work when it comes to distances in space over 400 LY. And a lot of room for error in things within the 400 LY range.

They say that triangulation is the best method for stars within this distance, but the minute angles, even taken 6 months apart, and about 186 million miles apart, are so small I feel even these are guesstimates.

The first technique uses triangulation (a.k.a. parallax). The Earth's orbit around the sun has a diameter of about 186 million miles (300 million kilometers). By looking at a star one day and then looking at it again 6 months later, an astronomer can see a difference in the viewing angle for the star. With a little trigonometry, the different angles yield a distance. This technique works for stars within about 400 light years of earth.

SOURCE

For farther than 400LY they use brightness measurements, which makes me chuckle when I see statements like 250 million LY, or a billion LY. They really don't know.

As far as relativity and time, well, I will go wipe the drool from my chin and leave that to others to speculate.

originally posted by: stosh64
a reply to: Bone75

IMHO, there is MUCH guess work when it comes to distances in space over 400 LY. And a lot of room for error in things within the 400 LY range.

They say that triangulation is the best method for stars within this distance, but the minute angles, even taken 6 months apart, and about 186 million miles apart, are so small I feel even these are guesstimates.

The first technique uses triangulation (a.k.a. parallax). The Earth's orbit around the sun has a diameter of about 186 million miles (300 million kilometers). By looking at a star one day and then looking at it again 6 months later, an astronomer can see a difference in the viewing angle for the star. With a little trigonometry, the different angles yield a distance. This technique works for stars within about 400 light years of earth.

SOURCE

For farther than 400LY they use brightness measurements, which makes me chuckle when I see statements like 250 million LY, or a billion LY. They really don't know.

As far as relativity and time, well, I will go wipe the drool from my chin and leave that to others to speculate.

Science does require some faith... Unless you want to do all the calculations yourself.

a reply to: MrMaybeNot

I am waiting three more months for my study of Andromeda, took the first reading in Dec.

OK, not really, lol.

I have 'faith' that those who do this kind of thing can guesstimate better than I.

I bet many here will disagree with you using faith pertaining to science. To me it is refreshing to hear someone say that science requires faith at times.

a reply to: Bone75

Didn't we launch a satellite or something from Earth like 60 years ago or something and it made it out of the solar system already? Sorry I don't follow it enough to even know if what I am saying is true, but even if it was launched 200 years ago (which it didn't..) that is still much less than 2.5 million years at the speed of light (which this satellite isn't travelling at either)....Honestly I think our timeframes to get out in the solar system to other areas is 99% a guess...It probably doesn't take anywhere near the time they think it does and we will find out soon enough I am sure....

ETA: www.space.com...

A spacecraft from Earth has left its cosmic backyard and taken its first steps in interstellar space.

After streaking through space for nearly 35 years, NASA's robotic Voyager 1 probe finally left the solar system in August 2012, a study published today (Sept. 12) in the journal Science reports.

Yeah, 35 years to get out of our solar system....I believe our timeframes are WAAAAAAY off and just speculation honestly....

a reply to: Chrisfishenstein

1) Our solar system is not 2.5 million light years in radius

2) The Voyager 1 probe is not travelling anywhere close to the speed of light

a reply to: GetHyped

Voyager 1 is traveling at 17,043 m/s, it would take 17,565 years at this speed to travel just one complete light year.

a reply to: andy06shake

That is correct, the nearest star to ours is Alpha Centauri, which is 4.37 light-years away from Earth. These distances are not guesswork but are factual. It would take the Voyager probe roughly 80,000 years to get there. That is only the closest star. To just get out of our galaxy would take quite a bit longer.

The interesting thing is that if you were travelling close to the speed of light or even just super fast, then you would age less rapidly than someone on Earth. While you were travelling close to the speed of light, the other galaxies would actually appear closer to us than they do to people on Earth - I think that is correct.

So in a way, your O.P. is correct -

According to commonly accepted science, if I were to take off from where I'm standing at the speed of light, and head towards the Andromeda galaxy, it would take me 2.5 million years to get there.

Quantum mechanics particle and wave theory might explain this. It says the light is both particle and wave, a point and everywhere.

Yet according to time dilation, the faster you go, the more time slows down. So even though it appears to everyone else that it took me 2.5 million years to get there, I would actually be much less than 2.5 million years old.

Did the particle travel anywhere, or did it quantum leap out of the wave and hit your eye? We don't see light travelling through space till it reflects of something, and/or hits the retina directly, its all dark, but something is in there.... Everything that ever happened since the very beginning.

How does science reconcile this paradox? How can they say definitively that it takes light from the Andromeda galaxy 2.5 million years to get here? Wouldn't that light be much younger than we perceive it to be?

It would be younger, but it still took that long to get here, once the initial front of the wave arrives and passes, is starlight quantum within the wave? I'm just guessing really.i suppose it comes down to relativity but I get what you are saying. The age of light at the speed of light would be 0 or timeless. It conflicts with our understanding that it must be x yrs old because it travelled x distance. Probably a lack of wording, termilogy, or perspective.

Einstein says that for something traveling AT the speed of light, time stops completely. No time passes.

So, if that were true, then a photon of light never experiences time as it travel through space:

From the perspective of a photon, there is no such thing as time. It's emitted, and might exist for hundreds of trillions of years, but for the photon, there's zero time elapsed between when it's emitted and when it's absorbed again.

Source:
Does light experience time?

However, Einstein also said that objects with mass (resting mass) can NOT ever travel at the speed of light. That's because as the object approaches the speed of light, its mass increases exponentially until it would become infinitely massive, requiring an infinite amount of energy to accelerate it to that speed (and there isn't an infinite amount of energy available in the universe). However, photons have zero resting mass (they only have mass due to momentum) and thus are not subject to to this increase in mass.

But yeah -- it is interesting to think that no time passes during the life of a photon. The photon from a star in the Andromeda Galaxy may have taken 2.5 million years to reach our eyes after being emitted by the star, but from the point of view of the photon, it reached our eye instantaneously after being emitted.

a reply to: darkbake

"The interesting thing is that if you were travelling close to the speed of light or even just super fast, then you would age less rapidly than someone on Earth."

Thats relativity for you and one of the many problems we face with regards communication between star systems never mind eventual colonization.

From our perspective here on Earth 1000s if not 100,000s of years may have passed by the time any signal never mind space-craft we sent actually reached its desired destination.

Seems the universe is destined to keep any emergent sentient life apart simply via the distances involved. Which is quite understandable given our tendency to destroy any new environment we come across.

There is no paradox. If it takes you 2.5 million years at light speed to reach the target many more years than that will have happened to the people on Earth during your travel. Time indeed would have slowed down for you but it would still have taken millions of years to get there and Earth would be far older. I don't know the equations to figure out how much longer would have passed on Earth. I hope this explanation helped.

originally posted by: stosh64
a reply to: MrMaybeNot

I am waiting three more months for my study of Andromeda, took the first reading in Dec.

OK, not really, lol.

I have 'faith' that those who do this kind of thing can guesstimate better than I.

I bet many here will disagree with you using faith pertaining to science. To me it is refreshing to hear someone say that science requires faith at times.

Why guesstimate tiny angles can be measured accurately in the same way that certain products such as micro chips can be manufactured, or engineering products machined to extremely high tolerances, just because YOU don't know how doesn't mean it can't be done.

If a photon could perceive reality, wouldn't the photon's reality be one dimensional?

originally posted by: stosh64
a reply to: Bone75

IMHO, there is MUCH guess work when it comes to distances in space over 400 LY. And a lot of room for error in things within the 400 LY range.

They say that triangulation is the best method for stars within this distance, but the minute angles, even taken 6 months apart, and about 186 million miles apart, are so small I feel even these are guesstimates.

The first technique uses triangulation (a.k.a. parallax). The Earth's orbit around the sun has a diameter of about 186 million miles (300 million kilometers). By looking at a star one day and then looking at it again 6 months later, an astronomer can see a difference in the viewing angle for the star. With a little trigonometry, the different angles yield a distance. This technique works for stars within about 400 light years of earth.

SOURCE

For farther than 400LY they use brightness measurements, which makes me chuckle when I see statements like 250 million LY, or a billion LY. They really don't know.

As far as relativity and time, well, I will go wipe the drool from my chin and leave that to others to speculate.

Those brightness measurements are a bit more complicated than the zero lines you spent explaining it (IE you dismissed it without even discussion)

It is all to do with certain variable stars which are a class of stars with an extremely narrow brightness range, temperature range, pulsation frequency. We use 'local' stars that we can get good paralax measurements on to calibrate the distance scale, and then do a brightness measurement of similar stars in order to push the measurement of longer distances.

the other are certain types of supernova which have extremely repeatable and predictable behaviours. So when we see one, we can watch it, watch the afterglow, and then give an extremely good prediction of the distance.

originally posted by: ErosA433 So when we see one, we can watch it, watch the afterglow, and then give an extremely good prediction of the distance.

"An extremely good prediction"? Compared to what? When's the last time someone got close enough to a supernova to say "Damn we're good!"? lol

a reply to: Soylent Green Is People

You know what bothers me - it isn't the OP's "paradox", I think I have that one pretty nailed down - it's the statement "the closer you get to the speed of light, the more your mass increases"..

The closer you get to light speed, the less time you experience and the shorter a distance you experience. You may recall that these numbers begin to approach zero. According to relativity, mass can never move through the Universe at light speed. Mass will increase to infinity, and the amount of energy required to move it any faster will also be infinite. But for light itself, which is already moving at light speed… You guessed it, the photons reach zero distance and zero time.

Read more at: phys.org...

How does this happen? Where does this mass come from?

originally posted by: Bone75
Yet according to time dilation, the faster you go, the more time slows down. So even though it appears to everyone else that it took me 2.5 million years to get there, I would actually be much less than 2.5 million years old.

Well, consider this: from your perspective, during the trip, you were not moving relative to yourself. Instead it is everything else that appears to be moving relative to you. Therefore, you don't see your clock slow down- you see everbody else's clock slow down. The people back on Earth, on the other hand, see you as moving, so they see your clock slow down.

However, you'll both agree on how long the trip took you, because from your perspective, the distance between you and the other galaxy contracted. So even though your clock ran at the normal speed during the whole trip, the distance you had to travel appear to be much shorter.