A universe full of dead aliens

Capt'n Midnight

Wibbs wrote: »

In some cultures today that don't have the colour and if you show them a colour wheel they just don't see blue. They usually see it as an continuation of/another green. There are many examples of this and that's within one species on the same planet. Imagine another species from a different environment and thousands, maybe millions, maybe billions of years ahead of us? Aliens like that would be truly alien.

Alien aliens ?

Intelligent life down here is more alien than most SciFi

Most mammals don't have full colour vision. Lots of other animals can see in the UV. And then there's the mantis shrimp.

The most intelligent animals on this planet, excluding primates things like are four legged carnivores - and some polydacty cats have opposible thumbs, and dolphins who don't have that many legs or hands. Further away there's crows , very unlike us , last common ancestor was 330 million years ago.

And then there are the cephalopods , half a billion years apart from us (and with the retina on the inside side of the eye , so no blind spots like us) And an octupus doesn't have a personality like we'd see in vertebrates. On different days they behave differently. And a very different repoductive strategy to tetrapods.


Bats and elephants communicate using sounds we can't hear. Many social animals use hormones. Cephalopods change their skin patterns. We are very visual , but others use smell far more. And then there's the fish and semi-aquatic egg-laying mammals of action that use electricity. Then there's the moths whose antennaes are tuned to the far-infra red.


And then there's culture.


Larry Niven's World of Ptavvs is worth a look too.

Fourier

Wibbs wrote: »

Thank god, cos my maths ability runs out when I run out of fingers, socks off for hard sums (found out I apparently have dyscalculia(sp). Thick is easier to spell and likely more accurate)

I just looked it up there, apparently you're more likely to be smart if you have dyscalculia!

The energies involved are massive. On that score and maybe I have this all arseways, but is course correction at those type of velocities a major issue? Would lateral G forces not be scarily high? OK it's hardly equivalent, but Im thinking in a car driving at 20 Kph you barely notice steering inputs, but at 200Kph you do. I'd be thinking at 10% light speed firing up the sideways thrusters would leave the crew as stains on the walls with blinking eyes?

Yes a severe issue, even more than you might think initially.

At these speeds, not only would lateral Gs be massive (to the point of questioning the ability of any metal to withstand them), but unless the ship is of very even composition different parts of the ship will pick up speed slightly quicker, which at relativistic speeds means time runs differently for it, making different parts of the metal hotter from the perspective of other parts (time being faster => molecules vibrate faster => hotter).

So turning, or even accelerating in an uneven way can cause one part of the ship to be ripped off and melt the rest. To say little of the crew.

EDIT: This is why many hard sci-fi authors have ships which are perfect spheres made of a very uniform superdense material like neutronium.

These days we know so much and more, we're aware of areas we don't know or quite know about, but I do wonder what a civilisation that was a million years in advance of us would know and be able to build.

This is more a response to your final three paragraphs, but I think as you mention, it's really Terra Incognita. One of the main reasons I post in the "I bet you didn't know that thread" is to kind of fight against the very certain sounding picture of the world one picks up from pop-science. We don't know how the universe began, we only have guesses on how it might develop, one can't really know how far our laws extend (i.e. what fraction of the total is the observable universe, almost certainly less than a thousandth). 100 years later we don't even know what quantum mechanics means, we just have a bunch of rules for calculating the chances of our equipment clicking/lighting up in various ways, but no picture as to what is causing those clicks.

The famous double slit experiment, where facing a hot cathode at a screen with two slits in front of it, causes the screen to develop alternating bright and dark lines. QM tells you the screen will develop the lines, the end. There are roughly twenty guesses as to what is going on (the various interpretations of QM), but I think this shows that we really know very little about the very small.

Aliens who may have left all this stuff behind long ago, or conceive of it in a different way, who knows?

ps200306

Wibbs wrote: »

The energies involved are massive. On that score and maybe I have this all arseways, but is course correction at those type of velocities a major issue? Would lateral G forces not be scarily high? OK it's hardly equivalent, but Im thinking in a car driving at 20 Kph you barely notice steering inputs, but at 200Kph you do. I'd be thinking at 10% light speed firing up the sideways thrusters would leave the crew as stains on the walls with blinking eyes?

Fourier wrote: »

Yes a severe issue, even more than you might think initially.

At these speeds, not only would lateral Gs be massive (to the point of questioning the ability of any metal to withstand them), but unless the ship is of very even composition different parts of the ship will pick up speed slightly quicker, which at relativistic speeds means time runs differently for it, making different parts of the metal hotter from the perspective of other parts (time being faster => molecules vibrate faster => hotter).

So turning, or even accelerating in an uneven way can cause one part of the ship to be ripped off and melt the rest. To say little of the crew.

EDIT: This is why many hard sci-fi authors have ships which are perfect spheres made of a very uniform superdense material like neutronium.

I'm not getting it. The forces involved in a lateral movement are completely independent of your forward speed. The reason it's not true in a car or aeroplane is because the tyres or flying surfaces are used to divert forward momentum into lateral movement, so the two are related up to the point that the surfaces start to slip. In effect you are colliding with the road surface or air. There's no such correlation when your forward and sideways movement are independent, as with side thrusters in a spacecraft (which is why those weaving, swooping X-wing fighters in Star Wars annoyed the face off me, even as a kid). Simple Galilean relativity requires that the forces are the same whether your forward speed is a hundred or a hundred million mph. You'll just need a bigger forward distance (and thus more advance warning) to take evasive action at high speed.

tac foley

Fourier wrote: »

There's currently nothing to suggest you could make such a system, the current theories of physics do not allow it to be built.

Although there is some evidence, depending on how you look at the evidence, that the subatomic world does have access to such a system. Question would then be more if it can be made to work for large objects like ourselves.

My post was in the nature of a light-hearted quip, rather than a reflection of our current scientific lack of ideas re extra-solar space travel.

Movies are full of 'here we are/there we are' drives, and are great fun, but they are not a subject for any kind of serious discussion until there is some scientific basis for further investigation.


tac

Fourier

ps200306 wrote: »

I'm not getting it

Wibbs's psot was in the context of avoiding interstellar debris. Certainly with advanced enough warning, the turn to avoid something could be made abitrarily gentle. However warning that far in advance is very unlikely, the ship would need a telescopic array with better resolving power than hubble attached to its hull. Most likely one would have to make the turn with special relativistic lateral velocities (note not Galilean) with the almost insurmountable stresses.

The only options are significantly sublight speeds, or ships which are uniform in shape with hulls made from exotic materials.

Capt'n Midnight

Fourier wrote: »

The only options are significantly sublight speeds, or ships which are uniform in ship with hulls made from exotic materials.

speeds far below the speed of light are the only option for the foreseeable future.

Dr. Bre

It’s world UFO day.

tac foley

Dr. Bre wrote: »

It’s world UFO day.

So today we might reasonably expect somebody, somewhere, to be abdu

dr.fuzzenstein

tac foley wrote: »

So today we might reasonably expect somebody, somewhere, to be abdu

Let me know what exactly they're looking for up there and if they're better than my proctologist.