The Future of Earth and Beyond!

[Jinto]

Originally Posted by DonQuigleone

I don't really know how to explain it correctly, but my view is that due to the fact that there is no set velocity for the universe, this is basically happening already. It's just background radiation, and it's the same regardless of your speed.

Depends what your exactly talking about... radiation can be particle-based (alpha-radiation, and I'ld also include neutrons and positrons here... typically going at below relativistic speeds - because their mass would require a large amount of energy to accelerate them to relativistic speeds) and energy-based (beta, x-ray/gamma - typically at relativistic speeds).
The particle based radiation is what I was talking about. The energy based radiation must be what you are talking about.

Originally Posted by erneiz_hyde

About the thing that even tiny particles could do significant damage to a vessel moving at very high speed. If we're that advanced already we should've thought about countermeasures. If we don't use hyperspace, we could create some sort of repellent field in front of the craft to sweep away any stray particles or something similar to that. If we used hyperspace, then this isn't even a problem. If we used space tunnels, we already had something that cancels singularity, why fear some little stray particle?

While I agree with the notion that it is certainly "easier" to deal with the tiny particles in contrast to accelerating large amounts of matter to relativistic speeds... I'ld really like to inquire what exactly is your scientific definition of hyperspace?

Originally Posted by synaesthetic

It's not particles that are an issue. It's macroscopic objects moving at significant relative velocities. Chunks of rock, iron-bearing meteorites, pieces of broken satellite, scrap metal, all of these things can punch holes in spacecraft.

Particles are a problem at relativistic speeds... however... you are right in that their destructive power pales in comparison to object on object collisions at relativistic speeds. If 4 kg of matter collide with another >= 4 kg of matter at relativistic speeds, you'ld end up with an energy conversion in the tsar bomba magnitude.

[erneiz_hyde]

Originally Posted by Jinto

While I agree with the notion that it is certainly "easier" to deal with the tiny particles in contrast to accelerating large amounts of matter to relativistic speeds... I'ld really like to inquire what exactly is your scientific definition of hyperspace?

Just your standard SF definition I think. It's a space that is isolated from normal space so disturbances from normal space would have no to very little effect inside the hyperspace. Or have my understanding of this SF trope wrong all this time?

[DonQuigleone]

Originally Posted by Jinto

Depends what your exactly talking about... radiation can be particle-based (alpha-radiation, and I'ld also include neutrons and positrons here... typically going at below relativistic speeds - because their mass would require a large amount of energy to accelerate them to relativistic speeds) and energy-based (beta, x-ray/gamma - typically at relativistic speeds).
The particle based radiation is what I was talking about. The energy based radiation must be what you are talking about.

I meant all radiation, particulate and energy. They are both problems out in space, and I doubt they'll be worse if you go faster. A lot of this particulate stuff will also just pass straight through, think neutrinos.

What you're talking about is essentially radiation, which is already a problem that is dealt with.

[Jinto]

Originally Posted by DonQuigleone

I meant all radiation, particulate and energy. They are both problems out in space, and I doubt they'll be worse if you go faster. A lot of this particulate stuff will also just pass straight through, think neutrinos.

What you're talking about is essentially radiation, which is already a problem that is dealt with.

Sorry, you are wrong for particle based radiation (which btw. does not include neutrinos (because they are considered to not really interact with matter anyway - so in a sense they are not considered under the main stream definition of nuclear radiation, but I don't have the time to discuss the fundamentals of nuclear physics with you). If you argued that there are different particle densitities in this universe, I'ld agree, but that would imply you don't want to visit neighbouring stars using relativisitc speeds but deep space.

What the sun emits within it's reach (< distance to heliopause) is definitly "low" speed particle radiation (solar wind)

Originally Posted by Wikipedia Heliopause

The heliopause is the theoretical boundary where the Sun's solar wind is stopped by the interstellar medium; where the solar wind's strength is no longer great enough to push back the stellar winds of the surrounding stars. Voyager 1 is expected to cross the heliopause by 2014. The crossing of the heliopause should be signaled by a sharp drop in the temperature of charged particles.

These winds from surrounding stars are particulate matter btw. most of it at sub-relativistic speeds.

[Jan-Poo]

Sci-Fi kinda exaggerated the concept of Hyperspace postulated as a consequence of general relativity in my opinion.

The basic principle is that being the space curved due to gravitational effects if you can somehow escape this gravitational force and travel in a straight path rather than following the curve you will effectively exit normal space (hence hyperspace) and save time due tp this shortcut.

The idea of the hyperspace being all flashy with all those fancy lights beaming all around is just an invention. And frankly since light follows the curvature of space once you enter hyperspace you shouldn't be able to see any light at all. Unless there's something we don't know about there.

Anyway my skepticism raises from what concerns how much the space is curved. Sci-Fi makes it look like hyperspace can make any travel almost instant, but the theory only talks about a shortcut. In other words it might as well be possible that a travel of 10 light years would be only shortened to 9.8 light years even going on hyperspace. Not worth the effort.

Wormhole theory has more credit to it, but I'd still expect several light years involved and it would be useless for (relatively) short distance travels.

The other common sci-fi theory of "folding space" or "space warp" rather than exploiting the existing curvature of space creates one. However this is also something I'm very skeptical about because I don't think that the energy cost required to achieve such a task will be cheap, and I don't think curving space can even be done lightly without creating some disturbance.

[DonQuigleone]

Originally Posted by Jinto

Sorry, you are wrong for particle based radiation (which btw. does not include neutrinos (because they are considered to not really interact with matter anyway - so in a sense they are not considered under the main stream definition of nuclear radiation, but I don't have the time to discuss the fundamentals of nuclear physics with you). If you argued that there are different particle densitities in this universe, I'ld agree, but that would imply you don't want to visit neighbouring stars using relativisitc speeds but deep space.

What the sun emits within it's reach (< distance to heliopause) is definitly "low" speed particle radiation (solar wind)

Do not confuse "Nuclear Radiation" (what you're taught about in chemistry and nuclear physics) with "Radiation". Nuclear Radiation is a subset of Radiation as a whole. Radiation is any type of particle (or energy) travelling through a vacuum (or not requiring a medium to travel through). Neutrinos are a type of Radiation, as would be any high speed particles in space. The "Solar Wind" is also Radiation.

Any particles encountered in space would behave as non-ionizing radiation, regardless of what speed you're going at.

Also, I was speaking purely in terms of deep space travel. Ultra high speed travel would not take place within a solar system, and it would not be strictly necessary, as the distances within a solar system are small compared to deep space. In deep space there is no solar wind. And besides that, high velocity particles already crash into us every second, in the form of background radiation. I find it difficult to imagine that it would be particularly different in space, besides the lack of a magnetosphere to protect you.

[jamieS]

Background radiation will only heat up the spacecraft, it won't apply any force because photons have no mass.

[lordshadowisle]

Originally Posted by jamieS

Background radiation will only heat up the spacecraft, it won't apply any force because photons have no mass.

A force will be exerted because EM radiation produces radiation pressure. Think solar sails, or radiometers (those black vanes in an evacuated chamber).

[Ithekro]

I'm thinking full on atoms and molecules here. Particles as in particulate matter. Things larger than the size of an atom. Things that have mass.

[DonQuigleone]

Originally Posted by jamieS

Background radiation will only heat up the spacecraft, it won't apply any force because photons have no mass.

Radiation can also include particles with mass. There are several types of radiation, including radiation (as in light), Thermal Radiation (which is also light), Nuclear Radiation (which can include light or particles) and more.

[jamieS]

I thought background radiation was just EM radiation with a very long wavelength, like radio and microwaves?

[Jinto]

Originally Posted by DonQuigleone

Do not confuse "Nuclear Radiation" (what you're taught about in chemistry and nuclear physics) with "Radiation". Nuclear Radiation is a subset of Radiation as a whole. Radiation is any type of particle (or energy) travelling through a vacuum (or not requiring a medium to travel through). Neutrinos are a type of Radiation, as would be any high speed particles in space. The "Solar Wind" is also Radiation.

I don't say that everything you said is wrong, just the way you try to exclude particular matter from your hypothesis to make your point is what I critizise. I was talking about the matter-based "nuclear" radiation (not even restricted to ionizing radiation, since neutrons can affect other matter even though they are not ionizing). What you must be aware of, is that if you talk about radiation in general, then particle radiation is a subset of it... in space anyway.

Now particle radiation is what I am talking about (and what is of concern at relativistic speeds), it is matter-based radiation that is typically not going at the speed of light (e.g. alpha-radiation and neutrons/positrons in the solar wind).

http://en.wikipedia.org/wiki/Alpha_particle

I would like you to read the part about Energy and absorption. Imo 15,000 km/s (5% of c) cannot be considered relativistic speed. (edit Wikipedia: "As noted, the helium nuclei that form 10-12% of cosmic rays are usually of much higher energy than those produced by all such nuclear processes, and are thus capable of being highly penetrating and able to traverse the human body and also many meters of dense solid shielding, depending on their energy" - so this will not gain much influence when approaching c... but the stellar wind is way worse (since it is much slower than an alpha particle resulting from natural alpha decay)... again Wikipedia: "The solar wind is divided into two components, respectively termed the slow solar wind and the fast solar wind. The slow solar wind has a velocity of about 400 km/s, a temperature of 1.4–1.6×106 K and a composition that is a close match to the corona. By contrast, the fast solar wind has a typical velocity of 750 km/s, a temperature of 8×105 K and it nearly matches the composition of the Sun's photosphere.[20] The slow solar wind is twice as dense and more variable in intensity than the fast solar wind. The slow wind also has a more complex structure, with turbulent regions and large-scale structures.").

Originally Posted by DonQuigleone

Any particles encountered in space would behave as non-ionizing radiation, regardless of what speed you're going at.

When there is something to interact with, then ionizing radiation will behave like ionizing radition (a vessel's hull is something to interact with).

Originally Posted by DonQuigleone

Also, I was speaking purely in terms of deep space travel. Ultra high speed travel would not take place within a solar system, and it would not be strictly necessary, as the distances within a solar system are small compared to deep space. In deep space there is no solar wind.

And no stars. Where there are stars there is a particle wind coming from these stars. Since stars are most often clustered into galaxies you will have a concentration of this stellar wind there.

Originally Posted by DonQuigleone

And besides that, high velocity particles already crash into us every second, in the form of background radiation. I find it difficult to imagine that it would be particularly different in space, besides the lack of a magnetosphere to protect you.

E = m*c²/(sprt(1 - v²/c²)) - m*c². The alpha particle has 5MeV at 0.05c lets assume we crash into it at 0.9c:

E1 = 5MeV
E2 = (1/sqrt(1- (0.9c)²/1c²)-1)/(1/sqrt(1-(0.05c)²/1c²)-1) * E1
E2 = 1.2942/0.00125 * 5MeV = 5GeV (roughly a 1000 times more energy)

Now lets assume you were hitting it at 0.95c:

E2 = 3.203/0.00125 * 5MeV = 13GeV (roughly 13,000 times more energy).

While approaching c the energy that must be absorbed when hitting an alpha particle grows exponentially.

But there is an additional effect... when going at the speed of light you will "catch" a lot more alpha particles in a certain amount of time than you would at stand still. At stand still a certain amount of alpha particles would pass an area at 0.05c. They are simply flying through that area. If a particle stream of the same density was now passing that area at 0.9c you'ld count a lot more particles in the same time... like 18 times more (I hope I did not disregard relativity rules here). So in the 0.9c example from above, you'ld actually had to absorb/reflect not just a 1,000 times more alpha-radiation energy but 18,000 times more alpha-radiation energy.

Then there would be additional relativistic effects like time expansion, but I am not sure to what extent this will influence the energy levels that have to be absorbed.

What we could debate now, is if it really makes a big difference if you travel at 0.9c or 0.999c (at least from the reference frame of a stand still observer).

[Jan-Poo]

It's pretty interesting Jinto but how high is the chance to encounter such particles in open space?

It might seem that it's high considering there's literally a sea of cosmic rays, but to my knowledge the space is so huge that even this sea might be quite diluted in the end.

For example the chance of clashing with an asteroid by passing trhough the asteroid belt is abysmal and this is still the solar system.

What am I wondering is if it isn't the case that the even in the situation of clashing with these particles the amount of matter encountered would be so scarce to not create any relevant hazard.

I may be very possible wrong but I'de be interested to see some confirmation or negation.

[Jinto]

Originally Posted by Jan-Poo

It's pretty interesting Jinto but how high is the chance to encounter such particles in open space?

It might seem that it's high considering there's literally a sea of cosmic rays, but to my knowledge the space is so huge that even this sea might be quite diluted in the end.

The cosmic rays and background radiation are not really of concern, since this is already very high energy radiation (at mostly relativistic speeds). What is more of concern are stellar winds and depending on where you are the interstellar medium (outside of the reach of stars' stellar winds).

Originally Posted by Jan-Poo

For example the chance of clashing with an asteroid by passing trhough the asteroid belt is abysmal and this is still the solar system.

What am I wondering is if it isn't the case that the even in the situation of clashing with these particles the amount of matter encountered would be so scarce to not create any relevant hazard.

I may be very possible wrong but I'de be interested to see some confirmation or negation.

The solar wind (which is rather weak in comparison to the stellar winds of other stars) at the distance of earth's orbit has an average density of 10 particles/cm³ (CMEs can be magnitudes more dense of course). So, the average pressure of this plasma is really low.
In average the solar wind has a speed of 500km/s or 0.16% the speed of light. An object with an exposed area of 1m² at stand still, would be hit with 500,000*10*1,000,000 particles per second (5x10^12 particles which translates into a pressure of 3.4×10^−9 N/m² - thats roughly 10^14 times less pressure than in earth's atmoshpere at sea level (101,000 N/m²)).
At 0.9c the particle count per time interval will increase approximately 500 times. And the kinetic energy of the particles will be roughly 1.29/(1.4*10^-6) or 1,000,000 times higher... so the average pressure should be 500,000,000 times higher (1.7 N/m² - which is still very low - provided that the vessel's shielding was perfect, because particle radiation with this pressure resulting from high energy particles would harm biological life forms).

Based on these estimations I have to conclude (and admit defeat ) that the average density of slow particles in space is not sufficient to create any relevant hazard (for future shielding technologies).

[DonQuigleone]

I also don't agree that in Deep Space (not near any stars, which is the vast majority of space, even in galaxies), you're as likely to encounter particles moving at relativistic speeds as non-relativistic speeds, and they all sort of balance out.

Space has no "stationary", what you might regard as stationary is, in fact, not. The sun for instance moves at 220km/s (relative to the galactic center), other objects faster or slower. There will be particles moving at every speed and direction imaginable. It would only be a major problem where there is a known quantity of particles, which in most of space does not apply, as most of space only has a smattering.

Anyway, you've acknowledged that it's probably not a major issue, so it may not be worth continuing further.

Another thing you have to bear in mind is that velocities in collisions at relativistic speeds don't add. If you were going at half of light speed and another object is also going at half of light speed, but the opposite direction, the two obviously don't see each other as going at light speed. I'm not sure what they'd see each other as though...

[Jinto]

Originally Posted by DonQuigleone

I also don't agree that in Deep Space (not near any stars, which is the vast majority of space, even in galaxies), you're as likely to encounter particles moving at relativistic speeds as non-relativistic speeds, and they all sort of balance out.

Technically its a system of interaction and constant generation of radiation. For example at the sun's heliopause the particles are slowed down because they are thinned out enough to not being able to go against the pressure of the interstellar medium. The plasma in this region is pretty much stationary (in reference to the sun). So, I have to assume that beyond this region there is more radiation with particles moving at relativistic speeds (otherwise they would certainly have been caught by stars that are more central in the galaxy (sun is supposed to be somewhere at an outer stretch of the galaxy).

Originally Posted by DonQuigleone

Space has no "stationary", what you might regard as stationary is, in fact, not. The sun for instance moves at 220km/s (relative to the galactic center), other objects faster or slower.

Though 220km/s in comparison to c is almost stationary.

Originally Posted by DonQuigleone

There will be particles moving at every speed and direction imaginable. It would only be a major problem where there is a known quantity of particles, which in most of space does not apply, as most of space only has a smattering.

I'ld imagine the closer you come to the center of the galaxy the denser the interstellar medium becomes (on average).

Originally Posted by DonQuigleone

Anyway, you've acknowledged that it's probably not a major issue, so it may not be worth continuing further.

Another thing you have to bear in mind is that velocities in collisions at relativistic speeds don't add. If you were going at half of light speed and another object is also going at half of light speed, but the opposite direction, the two obviously don't see each other as going at light speed. I'm not sure what they'd see each other as though...

That is why my calculations were always approaching speeds where one reference frame is considered stand still. If one reference frame is slow enough (<<c) it will be fairly accurate.

[Sabaku Kyu]

Apologies if it's been mentioned earlier, but has anyone heard of DARPA's 100-year spaceship initiative?

Obviously, it's barely in its conceptual phases and right now it seems like little more than a PR project, but the fact that DARPA is involved shows there's at least some real government interest in deep space exploration.

DARPA's seeking feasible ideas to make interstellar travel a reality within 100 years from now. I don't personally think that timescale is realistic (likely they just wanted a timeframe that would generate public interest). I believe we'll barely have manned exploration of our own solar system completed in 100 years, but the ambition is admirable. The fact is, moving into space is the only way to ensure long-term survival of the human race. It's estimated that within the next 5-10 years an Earth-like planet outside the solar system with conditions suitable for life will be found. There should definitely be intense research on deep space travel as soon as its found. The challenges are immense but not insurmountable.

- new energy sources need to be developed. Liquid propelled rockets require an insane amount of fuel for the speeds and distances required, compounded by the fact that more fuel adds more mass to the spacecraft, adding to the force needed for propulsion. Fusion or antimatter are probably the most likely alternatives

- fully self-sufficient environments with completely recyclable air and water systems need to be created. nothing can be wasted.

- artificial gravity needs to generated somehow, to prevent muscular atrophy and maintain bone density.

- proper shielding for collisions with particles at speeds approaching that of the speed of light (already popular discussion I see)

- advanced navigation systems are needed, not only will any targeted planets be orbiting a star, the planet's star is also in orbit about the galaxy.

It's entirely possible that the technology for these things is available within the next 100 years. However, it will be insanely expensive and only fundable through a massive international effort. So maybe a generation or two after that, when mankind has cut his teeth exploring/colonizing locations like Mars and Europa we can move onto other star systems.

[erneiz_hyde]

Btw, you guys must've heard about the impending gigantic magnetic storm from the sun that the scientific communities predicted could happen any minute now. Normally that wouldn't be too much a problem. However, it also coincides with this period of a major weakening of our earth's protective magnetic field because of our impending the-overdue-earth-pole-switch. And this combined situation is highly potential of permanently frying EVERY power-grid existing on planet Earth, effectively kicking Earth back to the Dark Ages.

The horror is that it could actually happen, unlike the zombie apocalypse. Now if this actually happened, this scenario wouldn't outright be apocalyptic, but our progress would be halted or even reversing for at least 10 years in the developed country to fully repair the power-grid and God-knows how long anywhere else, during which period we would essentially be living in a post-apocalyptic environmental situation.

Spoiler for let's try and imagine how the situation would look like:

no electricity means no water pump and no new gasoline produced anywhere, no new products of any kind being manufactured, no heating in the winter period too. anarcy, sacking, and plundering would be rampant for both survival and opportunistic needs. Government would be essentially gone since no form of long-range communication is possible which means the rise of small concentrated societies which governs themselves.war between these societies for control of resource is highly inevitable. Eventually guns could be the ultimate proof of might for the leader of the flock to try and control societies, because no new ones are being manufactured(or at least not as much). The rest would be resorting to melee or makeshift ranged weaponry to defend themselves. Horses and other animal rides would return to be the main form of transportation. etc etc

I try not to think too much about it and just enjoy life. But it is worrying information nonetheless and it sometimes creeps in me.

[AnimeFan188]

When only 1% are Employed:

"Technological change is rapidly killing entire industries and job categories
without replacing them. Across the board, incremental productivity
improvements are making it possible for employers to get by without hiring new
people (even the head of the biggest employer in the World has plans to replace
most of his workers with robots). However, that won’t be where we see the
greatest losses. Those losses will occur in the industries that are completely
gutted from the arrival of products and services that make them obsolete.

As this trend strengthens, we may see results similar to what we saw with the
agrarian economy. If that occurs, the extreme endpoint of this decline may be a
world where most of the commercial activity in goods and services we see today
— from education to health care to manufacturing to transportation to retail to
legal services — is accomplished by less than 1% of the people it used to
require.

That means only 1 of the hundred jobs being done currently will be left. More
strikingly, it’s very likely this won’t take the 200 years it took agriculture to go
from 95% of the population to less than 1%. It’s going to be much, much faster
this time due to the speed at which improvements can be distributed
(software/data). Given this catalyst, we may find ourselves more than half of the
way there within twenty years."

See:

http://www.homefreeamerica.us/1-employed/