Travelling to The Stars - My Mind Is Having Trouble Comprehending Some Things.

Greetings ATS Space Exploration Experts!

These are questions that I've wanted to ask in the Space Exploration forum for a long time, but didn't know how to word them. So, after 3 years of thinking about this, here goes..

ASSUMPTION:
When we look up at the stars, they aren't really where they appear to be. If you could instantly wish yourself to where you think a star is, you'd most likely find yourself in empty space. That star could actually be on the other side of the Earth AT THAT MOMENT, because the light we see left that star YEARS ago. (Is this correct thus far?)

QUESTIONS:
So, if you launch a ship towards a star system that is 10 light-years away, and that ship travels at the speed of light, how do you aim that ship? How would you be certain that something catastrophic didn't happen to that star/sun in the past 10 years? The $500 Billion Dollar mission would be a great economy booster, but could be a scientific bust if the target star is "gone" for some reason.

But, assuming the target star is still "alive and well", when would astronauts approaching that star begin to see it pretty much in front of their ship, instead of behind it, or on the side, above, below, etc.?

The obstacles and unknowns of traveling to objects that are light-years away, boggles my laymen mind. Maybe if we could travel FAST ENOUGH, and had some type of viewer to see how a star system is doing at that moment, I wouldn't be so dumbfounded. Watching and loving everything Star Trek related since 1968 has left me with totally false beliefs about how space travel REALLY works.

BIG THANKS to everyone who contributes a constructive reply!

-CareWeMust

p.s. I saw a movie 2 years ago at the theatre where astronauts went down to a planet to do some research. When they returned to the orbiting "mother ship" after a couple of days, the poor guy who stayed on the ship had aged 40 years! To this day, I don't understand that phenomena, or if that was merely made-up fiction by the writer. (Movie was called "Interstellar")

a reply to: carewemust
I can't say I'm answering with any expertise, just my personal thoughts and opinions and slight bit of knowledge, but here goes!

So, if you launch a ship towards a star system that is 10 light-years away, and that ship travels at the speed of light, how do you aim that ship?

I'm going to assume just like we do when launching probes towards planets in our solar system. Go by calculations of where it will be, and where we need to aim to meet up with it.

How would you be certain that something catastrophic didn't happen to that star/sun in the past 10 years?

We couldn't be certain. We can only go by what we know from observations. We've never observed a star just randomly pop out of existence so far, so it would be safe to say at our current knowledge and understanding as long as we pick a proper target it will still be there when we get there.

But, assuming the target star is still "alive and well", when would astronauts approaching that star begin to see it pretty much in front of their ship, instead of behind it, or on the side, above, below, etc.?

I would guess it would always be in front of them. Imagine someone throwing a curveball with a baseball that travels slow enough for you to be able to move at the same rate it does so by the time it reaches you it crosses the center of the plate. To you the ball will always look like its heading towards the center of the plate.

When they returned to the orbiting "mother ship" after a couple of days, the poor guy who stayed on the ship had aged 40 years!

That's a scientific theory with a lot of solid evidence to show for it. We don't know the true extent of it, but we do know that time dilation does exist.

(Movie was called "Interstellar")

I can say with confidence this is one of the best movies of all time

Lifecycle and demise of stars is well-understood. To predict such a thing would be within the scope of observational science (pun intended). However, collisions or other dealbreakers like Gamma Ray Bursts, maybe even nasty Klingons could be there waiting for you.

Traveling 10 light-years in 10 years narrows down the possibilities, but the real tragedy would be a long multi-generational trip at a few percent of light-speed, that does indeed reach a doomed objective.

As you approach your objective, the old light coming from it becomes newer all the time, and thus more 'correct' compared to the target's present location. If you're going fast enough (faster than light speed seems necessary), you will at some point overtake the object, all the time correcting your trajectory. If it hasn't gone nova, it should still be 'there'.

Now someone needs to explain to me how a single photon, exiting a star billions of light years away, manages to traverse all of space and time without hitting so much as a dust particle before it manages to enter my eye and hit my retina... for me to glory in, knowing what little I do then about the size of the universe and my place in it... and what happens to that photon at that moment, that has been traveling for so long? Does it get absorbed? Explode? Keep right on going through the back of my eyeball and out my skull to continue it's journey? Does it become one with my brain, an incredibly ancient donation of .... what, exactly?... added to whatever *I* am?

originally posted by: carewemust
That star could actually be on the other side of the Earth AT THAT MOMENT, because the light we see left that star YEARS ago. (Is this correct thus far?)

Nope.

The light you see might have left the stars decades ago but it's still travelling in straight line.

Stars move relatively to the galaxy, but so do we. It might have moved a tiny bit since it emitted light, but not to the point where it would be on the other side of the earth.

originally posted by: carewemust
So, if you launch a ship towards a star system that is 10 light-years away, and that ship travels at the speed of light, how do you aim that ship?

That's what the laws of physics are for. So we can make a model of the universe and estimate where we should "aim" the ship.

originally posted by: carewemust
How would you be certain that something catastrophic didn't happen to that star/sun in the past 10 years?

You wouldn't, bot over the lifespan of a star, such a chance is ridiculously small

a reply to: carewemust

In science-fiction they have imagined the following : imagine we launch today, in 2016, a ship with people(settlers) on it, they are either in hibernation or it's a multi-generational mission. This mission would take 600 years to arrive at its destination which is a distant habitable planet. Meanwhile on Earth, in 2116 we discover faster than light travel which reduce the 600 years trip to 6 months or even weeks. When the settlers arrive on this planet, in 2616, they discover that humans have settled 500 years ago and they have developed a new civilization !

a reply to: carewemust

Maths. To all your questions.

a reply to: carewemust

Astronomers and astrophysicists use 'sidereal time' as a way to plot the motions of stars. It allows them to predict where the star is going and exactly where it's been.

In basic terms, I picture it being similar to a top batter hitting a wicked curve-ball. The bat hits the ball where the brain has predicted it to be instead of always hitting thin air. If we shipped off to a star 10ly away, we'd make allowances for are moving planet and the transit of the star to aim ourselves in the right direction.

Damned if I know to steer a ship at light speed! It'd certainly need to be steerable just to get past Oort clouds and asteroid belts. It'd need a route that was utterly clear of debris and spend much of its travel time slowing down again. Man, travelling at 130mph makes steering a car feel edgy. Even with AI and computer assist, imagine the sensitivity of changing course at light speed? A millionth of a degree would lead to a massive difference in destination.

a reply to: carewemust

ASSUMPTION:
When we look up at the stars, they aren't really where they appear to be. If you could instantly wish yourself to where you think a star is, you'd most likely find yourself in empty space. That star could actually be on the other side of the Earth AT THAT MOMENT, because the light we see left that star YEARS ago. (Is this correct thus far?)

The apparent direction of a star from the surface of the Earth is a function of the Earth's rotation. Depending upon what type of magic fulfilled your wish, that would probably not be relevant.

QUESTIONS:
So, if you launch a ship towards a star system that is 10 light-years away, and that ship travels at the speed of light, how do you aim that ship? How would you be certain that something catastrophic didn't happen to that star/sun in the past 10 years? The $500 Billion Dollar mission would be a great economy booster, but could be a scientific bust if the target star is "gone" for some reason.

The "proper motion" of the nearby stars are relatively well known. We can predict with a fair degree of certainty where a star will be in three dimensional space at a given time, and these observations are bound to improve in the future. As has been pointed out, the life cycle of stars is understood, and it is unlikely that a chosen Sun-like star would be prone to cataclysmic changes. On the other hand, near lightspeed travel would be incredibly hazardous....

But, assuming the target star is still "alive and well", when would astronauts approaching that star begin to see it pretty much in front of their ship, instead of behind it, or on the side, above, below, etc.?

A ship travelling at relativistic speeds, that is, close to the speed of light, would experience certain phenomena that would render navigation nearly impossible. For reasons too complex to explain in a brief post, all of the stars within 180 degrees of the forward direction of travel would start to clump together in front of the ship and shift their light to increasingly energetic wavelengths. They would essentially be heading into a sort of gamma ray death beam. (Meanwhile, the stars on the trailing end would clump together aft and fade out into the far infrared.)

The obstacles and unknowns of traveling to objects that are light-years away, boggles my laymen mind. Maybe if we could travel FAST ENOUGH, and had some type of viewer to see how a star system is doing at that moment, I wouldn't be so dumbfounded. Watching and loving everything Star Trek related since 1968 has left me with totally false beliefs about how space travel REALLY works.

Our ability to observe the stars is improving all the time. Combining computers with telescopes that operate in a variety of wavelengths allows us to collect ever better data which can be used to model conditions in other solar systems. By the time our advances in propulsion allows the first intentional interstellar probes, we will have a fairly good idea of what they will find.

BIG THANKS to everyone who contributes a constructive reply!

-CareWeMust

You're welcome... and thank you for a pleasant diversion from the out of control political posts!

p.s. I saw a movie 2 years ago at the theatre where astronauts went down to a planet to do some research. When they returned to the orbiting "mother ship" after a couple of days, the poor guy who stayed on the ship had aged 40 years! To this day, I don't understand that phenomena, or if that was merely made-up fiction by the writer. (Movie was called "Interstellar")

Time moves at different speeds for different observers; this is one of those relativistic issues that is difficult to explain; you can search "time dilation" or "the twin paradox" for a fuller explanation than I could give here.

a reply to: carewemust

How would you be certain that something catastrophic didn't happen to that star/sun in the past 10 years? The $500 Billion Dollar mission would be a great economy booster, but could be a scientific bust if the target star is "gone" for some reason.

"Star gones" are pretty rare. They are called supernovas.

So, if you launch a ship towards a star system that is 10 light-years away, and that ship travels at the speed of light, how do you aim that ship?

We do it all the time inside the solar system, by aiming to intersect planets where they are going to be.

originally posted by: gosseyn
a reply to: carewemust

In science-fiction they have imagined the following : imagine we launch today, in 2016, a ship with people(settlers) on it, they are either in hibernation or it's a multi-generational mission. This mission would take 600 years to arrive at its destination which is a distant habitable planet. Meanwhile on Earth, in 2116 we discover faster than light travel which reduce the 600 years trip to 6 months or even weeks. When the settlers arrive on this planet, in 2616, they discover that humans have settled 500 years ago and they have developed a new civilization !

How cruel of the later settlers to zoom past the original settlers and not wake them up.....unless those first settlers have a guy called Kahn amongst them in which case I will let them off.

I doubt a multi generational ship would function as intended.
Generation two would likely turn around.

"ASSUMPTION:" is key here. Modern science has forgotten that Einstein's theories and "faster then speed of light is impossible" are based on many assumptions that are unexperimented, unobserved, and just guesses. These assumptions are holding humanity back from interstellar travel. We need to keep critically thinking and critically experimenting! Another drawback is greed. 200 companies try to invent new things, and even if they succeed they then shelf it from the rest and milk it for all the money and never release the found knowledge.


So open your mind to new possibilities and angles in experimentation. That is how physics has reached this point. Check out M.T. Keshe's theories and experiments for a whole new perspective on new possibilties of physics on youtube and at www.keshefoundation.org.

a reply to: Freeyourchains

Einstein's theories have been proven beyond a shadow of a doubt. On the other hand, Keshe is a con man and known hoaxer.

a reply to: carewemust
Came up with an analogy for your endeavor, put yourself in a empty warehouse blindfolded and several people are scattered, they can call you so you hear them and can walk to them, now if you can only take one step a minute and they can move or go silent (disappear)...

a reply to: Freeyourchains

It was also impossible for a while that the Earth was not the center of the universe. I think scientists should go in with the assumption, which I'm sure many do, not that it is impossible to go faster than the speed of light but instead that it just hasn't been discovered how to do it. I believe the key probably lies in adjusting time, but I'll leave that to the scientists. If students were taught from a young age not that things are impossible, but that we don't know how to do something yet, the world would be a better place.

I read a theory once that I like to believe could be true, that dark matter surrounding the solar systems, just outside the heliosphere, actually alters the light coming from other solar systems so we don't really know how close or far away another star is. Even though Voyager 1 has reached the edge, the instrumentation on board doesn't give very much useful information. Everything is speculative really, no one knows what is at the edge, just like no one knew what the environment was like outside Earth's atmosphere in the 1940's. For all we know Voyager passed a couple Borg motherships on the way to assimilate us, maybe it was assimilated itself!

a reply to: carewemust

Not an expert, however coming from a fellow layman, they could use visual observation, as the closer they get to the star, the least time it took for the light to get to you.

Example: star is ten light years away, as you travel for one light year, the current light you seenow only took 9 lights years to get to you, another year and it's 8, than 7, and so on till you're right in front of it.(or as close without getting burned up)

Billions of galaxies, their light arriving millions of billions of years after the fact, we can only ever 'know' what they looked like that long ago, based on technological restraints and our ability to see only a scant amount of the possible light frequency spectrum, and we can't ever know what those billions of galaxies are like now, or even if they still exist or have blown into smithereens.

The mind boggles.

I now return you to your regularly scheduled programming, about which unmitigated disaster is going to be elected President...

Photons do have to travel for billions of years before they reach us, and what happens to them during that time is open to conjecture. Gas and dust all play their part but gravity also has an effect. If light enters a gravity field it will be blue-shifted and if it emerges, it will be red-shifted. These combined, there are those of us who are in conflict with the 'expanding Universe' theory, that being down to observed light being red-shifted due to the afore mentioned physical constants. With the new science theory of Dark Matter sounding ever more extreme, coupled with a near hysterical claim that the Universe will not exist by the time we develop spacing travel (it apparently will have expanded over the event horizon). The question remains, will we reach the stars or will we have been incarcerated after lynching maddened scientists.

carewemust wrote:
QUESTIONS: So, if you launch a ship towards a star system that is 10 light-years away, and that ship travels at the speed of light, how do you aim that ship? How would you be certain that something catastrophic didn't happen to that star/sun in the past 10 years? The $500 Billion Dollar mission would be a great economy booster, but could be a scientific bust if the target star is "gone" for some reason.

Vector99 answered:
I'm going to assume just like we do when launching probes towards planets in our solar system. Go by calculations of where it will be, and where we need to aim to meet up with it.

Great thread, only just stumbled across it. I have never thought about that one.
I would assume Vector99 is correct in that we would have to do some predictive calculations as they do. My thoughts would be to take all the positions of the target over-time and then use some deep learning AI (Theano?) to project it's position forward based on how many light years away from us it is. The problem with this is we may not have enough data to accurately project forward its position when we arrive. So we would also have to mix in the known surrounding references we do have a lot of data for such as stars and planets, nearby and their offsets. Then map these all out to X,Y,Z co-ordinates or something. Now the trick with large X,Y,Z co-ords is that the numbers become maaaasssive. so we use the target as the local 0,0,0 and then project back to good ol earth. Because innacuracies creep in with larger numbers, we always know where earth is and should be able to correct some of those innacuracies. I'm not a maths genius and I can see how this starts to get really complex when you look into it deeper so I might just stop now because the rest is out of my realm of knowing.