all stars outside the Local Group of galaxies will no be accessible to us since they will be receding away faster than the speed of light.
Can anyone explain what this means?
Can anyone explain what this means?
Instead, new space is being created between all objects. This can cause the distance between two objects to increase "faster" than the speed of light, without either of the objects actually moving.
Anyone who thinks otherwise just fails to grasp the distances involved. They are so large as to be beyond understanding.
Anyone who thinks otherwise just fails to grasp exponential growth. They are so large as to be beyond understanding.
Do you mean to say humanity certainly could travel to the nearest star?
I'm skeptical that anything resembling humanity could because everlasting exponential growth requires infinite resources. And humanity evolved on an abundant--but far from infinite--gravity well.
To answer your question though, the main problem with space travel isn't physics (assuming you are ok with long travel times), it's economics. We have sent astronauts to the moon and probes all across the solar system. The main reason we don't do more though is because of how expensive it is. However, a thousand years of 2% growth (not a given but again, grandiose) means we would have 400 million times more money to possibly spend on space travel. A NASA budget 400 million times larger could certainly build and send a spaceship 4 light years to alpha centauri.
Now how long will we sustain exponential growth? Well that's anyones guess but I don't see us becoming resource constrained for a long long time. The sun produces 10^13 more energy than the world used in 2013 according to [0] and we have plenty of resources in the solar system to build with (and we can recycle more).
[0]: https://www.quora.com/How-much-energy-does-the-sun-produce-p...
I'd argue it's biology, not physics. Sending a rock to another star is easy. Sending a rock that can send back data is probably possible with our technology, but it's unlikely it would retain data transmission capabilities long enough to actually report back from another star. Sending a bunch of humans and keeping them alive the entire journey? It's not clear we can do that for a round trip to Mars, let alone an interstellar journey.
I honestly think we'll achieve this long before we're able to properly or effectively simulate a brain with computers of any kind.
Humanity is on the cusp of three major technological breakthroughs that will quite literally change everything.
1) AI. Even if we don't reach ASI in the near term, we'll have ANI to help us research new technologies in months/years rather than decades.
2) Asteroid Mining. Whether it's Musk/Bezos/A. N. Other, the very first time someone brings down an asteroid. It will herald the dawn of abundance for precious metals. What will happen to prices is another topic. But this will allow researchers to develop even more exotic materials.
With better materials resistant to heat, more conductive elements, etc, etc. Humanity be able to build what can only be dreamt of.
3) 7 Billion (now). 13 Billion with Mars, 50+ Billion with Europa, Titan, Ganymede, etc, etc, etc. There will be a time where Humans will stretch beyond this solar system. Imagine how many breakthroughs will be possible with 100m researchers and AI trying to crack something?
What will make this possible? With 1 and 2, we'll be able to finally crack fusion reactors. This will enable faster space travel than with current engines. Habitats will evolve from those initial Mars missions and will sprawl into mega cities. Who knows, there may even be Luxury apartments hovering in the upper atmosphere of Venus.
All this progress is exponential and if you stop to look around. The seeds are being sewn right now. By 2050, some things we consider Sci-fi will be reality.
Oh and I'll just throw this one in.
4) Nasa has been doing some work on the Alcubierre drive. Who is to say, that the issues that cannot be surmounted now, will be in the future? For those that want to know more. I'll leave a channel that goes into such things [0].
[0]: https://www.youtube.com/channel/UC2kkCGRqZWaSIK3BmLC8vaw/vid...
Say what? The idea that asteroid mining will enable material science revolutions is fanciful. We're not exactly short on metals (even precious metals). And interplanetary space is less extreme than environments we can create in terrestrial situations, so we're not going to find weird new stuff by poking around asteroids.
I don't know how likely this is. I imagine plenty of research has already been done on exotic alloys, however I wonder how much that research has been affected by economic constraints.
Last I checked, the price of most metals was greater than zero. They're commodity markets, so that means they're scarce. If you mean "available at any price," then we were not short on iron during the Bronze age or short on Aluminum during the early 1800s.
Think of ants crawling on the surface and a balloon which is being blown up.
Another way to think of it is velocity of an object is derivative of position in space over time. If space itself is moving your position relative to it isn't changing.
So space is being somehow created?! What if i have a large object, will the length of that object increase? Or will it break up?
If the cosmological constant were much larger than it is, atoms would have never formed at all.
Space is not "created", space-time is warped. Gravity is the deformation of space-time by mass/energy. The distance from point A to point B is measured by the time it takes for a light ray to get from A to B using the shortest path. But if you move objects with mass (or with energy) near A and B, the shortest path will change. Also, it's easy to measure distance in seconds when you know the speed of light.
[Edit: and, er, all that has something to do with dark energy?]
OK, but in that case, and if we still exist as a technological civilisation at that time (very doubtful) we might be able to use the effect for our own benefit. By building warp drives and er, not-quite-travelling faster than light, by expanding space around a ship, etc.
Both cars start driving off at 10 MPH in opposite directions. From an ant's perspective on top of one car, the other car looks to be going 20 MPH away from it. Then someone starts pulling the blanket underneath the cars from opposite ends at 5 MPH. Now it looks like the other car is going 30 MPH. Now imagine for each ripple on that blanket, another hand appears and starts to pull, and the outer edges are pulled at 5MPH from the reference point of the nearest ripple.
From the perspective of an ant on one end, it can eventually get to the point that the other car is warping off at 100MPH or more. And as this blanket spreads out more and more, things speed up more and more as well. The cars never technically exceed their speed limits of 10 MPH, but the space that they occupy is being pulled apart in a way that they seem to be exceeding 10 MPH from each other's perspectives.