gravity can pull us through the cosmos to where we want to go

[farsideofourmoon]

Some day in the far, far future mankind will travel the stars; this is inevitable, it is in our genes. Believing this I have been contemplating how we get to where we want to go. I do not believe we can carry enough fuel to propel us, nor do I believe we could find the fuel we need along the way.

Having said that the only choice we have is to use another source of energy that we have not considered before. That source of energy gravity. Gravity has an almost limitless power; it holds planets in orbit around our sun and solar systems together.

I believe we need to find a way to use the pulling force of gravity to pull us in the direction we want to go. We lock on to the gravity waves of a far-off galaxy and let it pull us in that direction. The speed at which we travel will along this wave will increase exponentially exceeding the speed of light and beyond.

Just a thought

What's your thoughts on this-?

[Ghideon]

2 hours ago, farsideofourmoon said:

I believe we need to find a way to use the pulling force of gravity to pull us in the direction we want to go.

Gravitational slingshot have been used for quite some time, for instance to accelerate Voyager probes. It's a useful idea, at least to accelerated in solar system*. https://en.wikipedia.org/wiki/Gravity_assist

 

2 hours ago, farsideofourmoon said:

We lock on to the gravity waves of a far-off galaxy and let it pull us in that direction. The speed at which we travel will along this wave will increase exponentially exceeding the speed of light and beyond.

Just a thought

What's your thoughts on this-?

I do not know what "lock on to gravity waves" means. But exceeding the speed of light in vacuum, gravitationally assisted or not, is not possible in any accepted mainstream theory AFAIK. 

 

*) Of course it works outside solar system as well but I do not think the time scales are practical. 

[Strange]

2 hours ago, farsideofourmoon said:

We lock on to the gravity waves of a far-off galaxy and let it pull us in that direction.

Galaxies do not create significant gravitational waves (note that "gravity waves" are something completely different). And even the "large" gravitational waves we can detect from black holes only move things by a minute amount. There isn't enough energy to move anything much. Plus, it would just move things sideways and then back again. Not propel you anywhere.

[joigus]

Gravity won't do the trick. There's just not enough energy and nothing can move faster than light, locally speaking. As Strange says, gravitational waves need really powerful sources to be triggered, as black-hole collisions, plus they're really feeble, and don't really induce linear accelerations in clusters of matter, but just space-time distortions in two mutually perpendicular directions. It's just like a blip on the radar screen, so to speak.

The Alcubierre metric is another far-fetched possibility AFAIK, not free from inconsistencies.

And then the only reasonable possibility in principle that I can think of is getting work from the huge storage of mc^2-energy in matter, maybe by capturing free antiparticles from cosmic rays and guiding them to ordinary matter that would act as fuel/target. But that is a far cry, I suppose. I'm a theorist, so I really can't tell with any degree of accuracy. There are many experimentalists/engineers here that can judge much better than me how much of a crazy idea the latter would be.

Edited May 13, 2020 by joigus
mistyped

[Strange]

2 hours ago, Ghideon said:

Gravitational slingshot have been used for quite some time, for instance to accelerate Voyager probes. It's a useful idea, at least to accelerated in solar system

And, even simpler, in the case of the Apollo missions, there is a point where the gravitational force of the Moon exceeds that of the Earth and the craft starts falling towards the Moon (and similarly for the return journey, falling back to Earth).

[Janus]

7 hours ago, farsideofourmoon said:

Some day in the far, far future mankind will travel the stars; this is inevitable, it is in our genes. Believing this I have been contemplating how we get to where we want to go. I do not believe we can carry enough fuel to propel us, nor do I believe we could find the fuel we need along the way.

Having said that the only choice we have is to use another source of energy that we have not considered before. That source of energy gravity. Gravity has an almost limitless power; it holds planets in orbit around our sun and solar systems together.

I believe we need to find a way to use the pulling force of gravity to pull us in the direction we want to go. We lock on to the gravity waves of a far-off galaxy and let it pull us in that direction. The speed at which we travel will along this wave will increase exponentially exceeding the speed of light and beyond.

Just a thought

What's your thoughts on this-?

I think you've succumbed to a common misconception about gravitational waves ( the term "gravity wave" actually refers to something like ocean waves, which are affected by gravity)

Gravitational waves are not the source of, nor the means by which the "force" of gravity is mediated.  Gravity is a field.  Gravitational waves just carry information about changes in the field. 

The gravitational attraction between masses would exist even in a situation where no gravitational waves were present.

[Ken Fabian]

8 hours ago, farsideofourmoon said:

Some day in the far, far future mankind will travel the stars; this is inevitable, it is in our genes. Believing this I have been contemplating how we get to where we want to go. I do not believe we can carry enough fuel to propel us, nor do I believe we could find the fuel we need along the way.

Having said that the only choice we have is to use another source of energy that we have not considered before. That source of energy gravity. Gravity has an almost limitless power; it holds planets in orbit around our sun and solar systems together.

I believe we need to find a way to use the pulling force of gravity to pull us in the direction we want to go. We lock on to the gravity waves of a far-off galaxy and let it pull us in that direction. The speed at which we travel will along this wave will increase exponentially exceeding the speed of light and beyond.

Just a thought

What's your thoughts on this-?

I don't think there is anything inevitable about interstellar travel and it is living on Earth, not space, that is "in our genes"; we will be remaking the environment around us to mimic the conditions of Earth wherever we go. I suspect the urge to seek new horizons when opportunities appear constrained may be in our genes - a primitive urge that worked well when humans were not yet spread across a world that was overflowing with natural and readily exploitable resources. I don't think it is so well suited to extremely hostile environments; we need well made plans with high levels of confidence for things that complex, not primitive urges and optimism.

I also have serious doubts about colonising any planets that have their own life - even unicellular "primitive" life; not only because that biology and biochemistry, uncontaminated, may be the most valuable resource such a planet has, there is a high likelihood of biochemical incompatibility, poisons and allergens. And any mission that can reach another star ought to be capable of builing operating space habitats - and probably find that easier than attempting a colony on a planet.

I agree that carrying enough fuel and other essential resources will be very difficult, however I think the "most possible" means of crossing interstellar space as I see it will rely on fuel found along the way and it will not be anything like a one shot trip; if self reliant colonisation of deep space objects becomes possible and new colonies are preferentially chosen further along a line to another star then in a distant future humans could reach there. Each colony would have to grow large enough to be a large industrial economy - nothing less being capable of the high technology requirements for survival, growth and providing the technology for the next colonisation.

I have serious doubts about any direct travel across interstellar distances in one go; any ship itself (or fleet) would have to carry the equivalent of a large, advanced - and working - industrial economy to sustain itself over the extreme distances and multigenerations of time. I am not convinced that will be possible.

Gravity as a way to get ships to where you want? The difficulties of interstellar travel are enormous and gravity is not a space 'drive'. There is no known way to get it to preferentially attract any spacecraft in a chosen direction to the exclusion of existing local gravitational fields and unlikely such technology will be possible.

[zapatos]

10 hours ago, farsideofourmoon said:

I do not believe we can carry enough fuel to propel us, nor do I believe we could find the fuel we need along the way.

Believe it. The first spacecraft was propelled toward another star and the galaxy at large 43 years ago. It's not like driving on a highway. Once you get up to speed you can turn off the engine and coast for the rest of the trip.

Quote

Voyager 1 entered interstellar space in August 2012, nearly 35 years after blasting off, scientists announced Thursday (Sept. 12). As it leaves our solar system behind, the robotic spacecraft is streaking toward an encounter with a star called AC +79 3888, which lies 17.6 light-years from Earth.

https://www.space.com/22783-voyager-1-interstellar-space-star-flyby.html

[MigL]

Oh sure, Zap.
And when  V Y GER  comes back, in about 200 years, after having sustained damage and merging with an alien probe, looking for its creator and threatening to destroy the world...
No, wait...
That's a movie.

[joigus]

7 hours ago, MigL said:

Oh sure, Zap.
And when  V Y GER  comes back, in about 200 years, after having sustained damage and merging with an alien probe, looking for its creator and threatening to destroy the world...
No, wait...
That's a movie.

LOL. There's also the 'minor' problem of slowing the hell down from near to 3x10^8 ms^⁻1 to near 0. That takes some braking capacity.

[farsideofourmoon]

On 5/14/2020 at 5:06 AM, joigus said:

LOL. There's also the 'minor' problem of slowing the hell down from near to 3x10^8 ms^⁻1 to near 0. That takes some braking capacity.

I agree that this is a far-off idea and yet it has generated some thoughts expressed here. Mankind will travel the stars unless we destroy ourselves first.

You asked how we are going to slow down to near zero and I say we do not have to. Everything in outer space is in motion. All we must do is match that speed of the nearby object and once done we are at zero relative to the other object.

I agree that using the pull of gravity of a far off galaxy is nothing less than farfetched but we do need to start thinking out of the box if we are ever going to get to where we want to go.

Inventions do not come by chance. Someone got an idea that was far-fetched and turned it into a reality.

Science fiction is a genre of speculative fiction that typically deals with imaginative and futuristic concepts such as advanced science and technology, space exploration, time travel, parallel universes, and extraterrestrial life. Wikipedia

Fiction generally is a narrative form, in any medium, consisting of people, events, or places that are imaginary—in other words, not based strictly on history or fact. In its most narrow usage, fiction refers to written narratives in prose and often specifically novels, though also novellas and short stories. Wikipedia

At 70 with little to nothing to do I come up with wild ideas and express them on talk boards like this one. My doctor told me that this is a healthy thing to do so I do it.

There is no conclusion or end product to this discussion, it is just a way to express one’s thoughts.

It’s been fun for as long as it lasted.

Edited May 17, 2020 by farsideofourmoon

[joigus]

2 hours ago, farsideofourmoon said:

You asked how we are going to slow down to near zero and I say we do not have to. Everything in outer space is in motion. All we must do is match that speed of the nearby object and once done we are at zero relative to the other object.

So if I understand you correctly, and I think I do, you're proposing to go after a galaxy that's receding from us at close to the speed of light (because of the universe's expansion) by going after it at close to the speed of light, and then, you will:

1) Catch up with it after having given the galaxy a head start of 14 billion-odd years

2) When you do, you will be there seeing it at rest from your spaceship

Do you see where the problem is?

Or maybe it's nearby, in which case it's not receding very fast from us (Hubble's law,) but a really considerably head start is still there, and if you want to catch up with it, you will have to squeeze the brake!

3 hours ago, farsideofourmoon said:

we do need to start thinking out of the box if we are ever going to get to where we want to go.

Out of the box is OK with me. What you're proposing is not out of the box. You can't even see the box right now.

And, believe me, I applaud your enthusiasm and share that longing with you of embracing the stars.

[farsideofourmoon]

At some point in the future we will be visited by others in the cosmos if not already, we can then ask them how they got here. Until then one guess is as good as another

(:-

[Mordred]

That is a common error. We can predict far more than we can accomplish through technology.

 We know the limitations of space travel. We also know the consequences of near c velocities.

 The near c or greater than c velocities are incredibly problematic when you study the physics and time aspects. Even the Alcubierre drive has consequences such as gamma ray production. ( It could literally radiate your destination)

[Endy0816]

3 hours ago, Mordred said:

That is a common error. We can predict far more than we can accomplish through technology.

 We know the limitations of space travel. We also know the consequences of near c velocities.

 The near c or greater than c velocities are incredibly problematic when you study the physics and time aspects. Even the Alcubierre drive has consequences such as gamma ray production. ( It could literally radiate your destination)

 

Does the math say anything about causality issues if your travel was to somewhere in the Unobservable Universe?

 

[Mordred]

One can assume the unobservable portion near our region of shared causality (observable universe) will have the same laws of physics. Ie GR still applies (including the speed limit)

[Dord]

8 hours ago, Mordred said:

We can predict far more than we can accomplish through technology.

Quite right, I'm still waiting for my Back to the Future Hoverboard...

[farsideofourmoon]

17 hours ago, Mordred said:

We know the limitations of space travel. We also know the consequences of near c velocities.

I disagree, we only know what we know now. At one point in our history people believed the earth was flat. We have moved beyond that.

Today we believe the speed of light is the ultimate speed, tomorrow we may think otherwise.

I honestly believe mankind will overcome the speed of light and at some point, in the far future we will travel the stars if and only if we do not destroy ourselves first.

[zapatos]

18 minutes ago, farsideofourmoon said:

I honestly believe mankind will overcome the speed of light

Is this belief based in science or in emotion?

[Janus]

5 minutes ago, farsideofourmoon said:

I disagree, we only know what we know now. At one point in our history people believed the earth was flat. We have moved beyond that.

Today we believe the speed of light is the ultimate speed, tomorrow we may think otherwise.

I honestly believe mankind will overcome the speed of light and at some point, in the far future we will travel the stars if and only if we do not destroy ourselves first.

Issac Asimov wrote an article about this called The Relativity of Wrong

We once thought the world was round, and then we corrected that to it being a sphere. That was further corrected to being an oblate spheroid, and later, further refinements were made.

The point is that this represents a series of refinements, each step being a smaller adjustment to the previous.  When it comes to the Earth's shape, we will never again see such a large shift as between flat Earth and round Earth.   Just because we once thought it was flat and now believe it to be round doesn't mean that some day we will conclude that is is shaped like a tetrahedron.

Likewise, any correction to Relativity would still need to fit our present observations of the universe, which do indicate that c is a natural speed limit built into the universe. 

While we can never absolutely be sure that there might not be a way around this, there is no reason to believe that this will ever be the case.

It is entirely possible( maybe even likely) that c is an insurmountable barrier.

It is important not to let what you would prefer to be true to influence what you believe to the be true.

As pleased as I would be if it turned out that the universe was populated with advanced civilizations and that FTL travel between star systems was practical,  I can't bring myself to believe it to be true given the lack of any credible evidence for it.

 

 

 

 

[farsideofourmoon]

1 hour ago, zapatos said:

Is this belief based in science or in emotion?

It’s based-on inevitability

(:-

1 hour ago, Janus said:

As pleased as I would be if it turned out that the universe was populated with advanced civilizations and that FTL travel between star systems was practical,  I can't bring myself to believe it to be true given the lack of any credible evidence for it.

During our lifetime we will not find an answer that we all would agree on so the debate will continue long after you and I are gone.

Now back to the here and now that can be understood, and changes that can be made made

so i am off the the realm of reality once again

[zapatos]

4 minutes ago, farsideofourmoon said:

It’s based-on inevitability

(:-

That kind of fantasizing is certainly enjoyable which is why science fiction is so popular. But this is a science site and you are in the physics section. More is required to maintain a discussion.

[Strange]

12 minutes ago, farsideofourmoon said:

It’s based-on inevitability

Belief, then.

There is a strange idea, poplar with some people, that "everything in science is wrong." 

That is incorrect, of course. Not everything is science is "exactly right." But almost nothing is completely wrong.

Apart from the (slightly mythical) flat Earth, there have been very few scientific theories that turned out to be completely wrong. Phlogiston is almost the only serious example. 

 

[farsideofourmoon]

19 minutes ago, zapatos said:

That kind of fantasizing is certainly enjoyable which is why science fiction is so popular. But this is a science site and you are in the physics section. More is required to maintain a discussion.

I know when I don't belong so I will be on my way

wish you and yours a great day and beyond

[zapatos]

6 minutes ago, farsideofourmoon said:

I know when I don't belong so I will be on my way

wish you and yours a great day and beyond

"To infinity...and beyond!" 😃