Search found 1110 matches

by tomandlu
Fri May 10, 2019 4:28 pm UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2934
Views: 701601

Re: Miscellaneous Science Questions

yeah, if instead of being in freefall, you were firing a jetpack, it'd have some additional energy contribution. Is that what you're thinking of? I'm not sure what you mean exactly by "impact on relativity." I think I'm being stupid. Thinking about it, and afaik, freefall has no impact on...
by tomandlu
Fri May 10, 2019 3:29 pm UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2934
Views: 701601

Re: Miscellaneous Science Questions

Yet another relativity question...

At the centre of the Earth, you would be in a state similar to freefall*, yet at the bottom of a gravity well. Does the freefall bit have any impact on relativity or just the gravity well?

* well, identical, provided you mean the sun.
by tomandlu
Fri May 10, 2019 2:26 pm UTC
Forum: Fictional Science
Topic: Seveneves - confused (spoilers)
Replies: 1
Views: 1478

Seveneves - confused (spoilers)

I'm reading Seveneves, and I'm a bit confused by the layout of the various space structures in the latter section of the book (aka "Five thousand years later"). Google hasn't helped me much... The habitat ring is a thin continuous band around the Earth - is it geosynchronous? The Eye is th...
by tomandlu
Fri Mar 15, 2019 10:14 pm UTC
Forum: Fictional Science
Topic: A Universe that's just two massive balls... fnar
Replies: 24
Views: 1710

Re: A Universe that's just two massive balls... fnar

They would collide at their escape velocity, multiplied (I think) by sqrt(2) on account of they're each accelerating the other. Why would escape velocity act as a limit on their final speed? Is it just how the maths works out? A sort-of galactic Achilles and the Tortoise IYSWIM? At escape velocity,...
by tomandlu
Fri Mar 15, 2019 9:51 am UTC
Forum: Fictional Science
Topic: A Universe that's just two massive balls... fnar
Replies: 24
Views: 1710

Re: A Universe that's just two massive balls... fnar

They will collide at almost c. Relativity ensures they can't be approaching each other at greater than c. How does that work when a stationary observer watches to objects hit when both are travelling at near-C? Can I not observe a single object travelling left to right at near-C? Observer in the ce...
by tomandlu
Fri Mar 15, 2019 9:49 am UTC
Forum: Fictional Science
Topic: A Universe that's just two massive balls... fnar
Replies: 24
Views: 1710

Re: A Universe that's just two massive balls... fnar

They would collide at their escape velocity, multiplied (I think) by sqrt(2) on account of they're each accelerating the other. Why would escape velocity act as a limit on their final speed? Is it just how the maths works out? A sort-of galactic Achilles and the Tortoise IYSWIM? At escape velocity,...
by tomandlu
Thu Mar 14, 2019 8:52 am UTC
Forum: Fictional Science
Topic: A Universe that's just two massive balls... fnar
Replies: 24
Views: 1710

Re: A Universe that's just two massive balls... fnar

gmalivuk wrote:They would collide at their escape velocity, multiplied (I think) by sqrt(2) on account of they're each accelerating the other.


Why would escape velocity act as a limit on their final speed? Is it just how the maths works out? A sort-of galactic Achilles and the Tortoise IYSWIM?
by tomandlu
Thu Mar 14, 2019 8:49 am UTC
Forum: Fictional Science
Topic: A Universe that's just two massive balls... fnar
Replies: 24
Views: 1710

Re: A Universe that's just two massive balls... fnar

Xanthir wrote:They will collide at almost c. Relativity ensures they can't be approaching each other at greater than c.


How does that work when a stationary observer watches to objects hit when both are travelling at near-C? Can I not observe a single object travelling left to right at near-C?
by tomandlu
Thu Mar 14, 2019 8:46 am UTC
Forum: Science
Topic: What if the second law was breakable?
Replies: 72
Views: 5686

Re: What if the second law was breakable?

It sounds as though you could get a nice SF story about intelligent races struggling to extract enough energy to keep going at the end of the universe, seeking out the boundaries and resources, and scavenging each other.

Not a million miles, I suppose, from the end of the cities in flight stories.
by tomandlu
Wed Mar 13, 2019 4:08 pm UTC
Forum: Fictional Science
Topic: A Universe that's just two massive balls... fnar
Replies: 24
Views: 1710

A Universe that's just two massive balls... fnar

What would happen if the universe just consisted of two very massive balls, several thousand light-years apart? My best guess is: ⋅ The balls would very slowly start accelerating towards each other ⋅ As the distance between them decreased, the acceleration would build ⋅ ...
by tomandlu
Mon Mar 11, 2019 1:08 pm UTC
Forum: Science
Topic: What if the second law was breakable?
Replies: 72
Views: 5686

Re: What if the second law was breakable?

Some tricky wording being thrown around - To be clear, all of the stars have to die in order to reduce all matter to a state where no more work can be done. So the question of whether or not the death of the stars could stop them is moot. The aliens themselves have to die too. The final composition...
by tomandlu
Mon Mar 11, 2019 11:35 am UTC
Forum: Science
Topic: What if the second law was breakable?
Replies: 72
Views: 5686

Re: What if the second law was breakable?

Drifting into the realms of SF here, but if we assume one intelligent species, wouldn't they keep reducing all matter to a state where no useful work remained in the universe? Given sufficient time, yes. However, the necessary span of time may be long enough for most stars to die of old age in the ...
by tomandlu
Sat Mar 09, 2019 9:58 am UTC
Forum: Science
Topic: What if the second law was breakable?
Replies: 72
Views: 5686

Re: What if the second law was breakable?

Drifting into the realms of SF here, but if we assume one intelligent species, wouldn't they keep reducing all matter to a state where no useful work remained in the universe?
by tomandlu
Fri Mar 08, 2019 8:21 am UTC
Forum: Science
Topic: What if the second law was breakable?
Replies: 72
Views: 5686

Re: What if the second law was breakable?

Okay, I'm going to have to keep asking/saying stupid things... Would the following statements be true? Presumably not, but why not? ⋅ Max entropy is not consistent with either an expanding or contracting universe, since both of those scenarios still contain useful energy ⋅ Howeve...
by tomandlu
Thu Mar 07, 2019 2:53 pm UTC
Forum: Science
Topic: What if the second law was breakable?
Replies: 72
Views: 5686

Re: What if the second law was breakable?

What sort of matter would make up a universe of total entropy?

Presumably, there's no electro-magnetic activity of any kind? Just (statistically) undifferentiated mass?

Is such a universe consistent with an ever-expanding universe?

Is it consistent with a contracting one?
by tomandlu
Tue Mar 05, 2019 9:05 am UTC
Forum: Science
Topic: Circadian Clock
Replies: 15
Views: 1651

Re: Circadian Clock

For real fun and games, read up on Richard Feynman's experience of messing about with day-lengths...
by tomandlu
Fri Feb 08, 2019 3:41 pm UTC
Forum: Language/Linguistics
Topic: Has anyone ever made a word square?
Replies: 31
Views: 12391

Re: Has anyone ever made a word square?

Here's mine after 20 mins arsing around...

Code: Select all

l a d s
a c r e
t i e r
e d g e
by tomandlu
Mon Jan 14, 2019 9:35 am UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2934
Views: 701601

Re: Miscellaneous Science Questions

Eebster the Great wrote: It also makes me wonder what is the defining distinction between carnivores and omnivores if even a "hypercarnivore" can get nearly a third of its energy from plants.


At a guess, an omnivore can survive purely on a herbivore diet, but a carnivore must have meat.
by tomandlu
Fri Jan 11, 2019 11:34 am UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2934
Views: 701601

Re: Miscellaneous Science Questions

p1t1o wrote:Please don't accidentally disprove all of existence guys, I just started looking for a house.


As long as it's not in Orqwith, you should be fine...
by tomandlu
Sun Dec 30, 2018 7:58 pm UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2934
Views: 701601

Re: Miscellaneous Science Questions

That's ridiculous, thus the premise must be false, and thus the identically-premised argument about the *start* of the universe must be false. There was no start, the universe is an eternal thing. This is starting to remind me of Bolztmann's Brain... I'd agree (I think) - since the conclusion to th...
by tomandlu
Fri Dec 28, 2018 6:58 pm UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2934
Views: 701601

Re: Miscellaneous Science Questions

The universe cannot be infinitely old, since if it was, it could never have reached the present moment - true or false? I really don't see how B follows from A, and people taking guesses seem to be thinking very differently from you. I think the keyword is "old". With no starting point, c...
by tomandlu
Fri Dec 28, 2018 5:16 pm UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2934
Views: 701601

Re: Miscellaneous Science Questions

doogly wrote:What you are proposing is that because there is an infinite extent in one direction, there cannot exist points at some finite distance from the origin. This makes no sense.


I was more thinking of infinite in both directions - it started an infinite amount of time ago being the significant point.
by tomandlu
Fri Dec 28, 2018 4:32 pm UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2934
Views: 701601

Re: Miscellaneous Science Questions

There are an infinite number of points between 0 and 1, and yet Zeno's arguments are still flawed. There are also an infinite number of points between zero and infinity. If the tortoise started with a 1% lead, the hare would never have caught it... What I'm saying is that, yes, it's silly to split ...
by tomandlu
Fri Dec 28, 2018 2:11 pm UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2934
Views: 701601

Re: Miscellaneous Science Questions

The universe cannot be infinitely old, since if it was, it could never have reached the present moment - true or false? Extremely false. This is like classic Zeno level nonsense. Aren't (most/all?) of Zeno's Paradoxes about creating infinities out of finite things? This seems to be the opposite IYS...
by tomandlu
Fri Dec 28, 2018 10:41 am UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2934
Views: 701601

Re: Miscellaneous Science Questions

The universe cannot be infinitely old, since if it was, it could never have reached the present moment - true or false?
by tomandlu
Mon Dec 10, 2018 10:36 am UTC
Forum: Science
Topic: Biology: Wolves vs. Humans
Replies: 45
Views: 7566

Re: Biology: Wolves vs. Humans

When people are attacked by dogs, they usually do not fight back and attempt to escape instead or dislodge the jaws, which is futile. But if they were determined to kill it from the outset, things would go very differently. If dogs just fastened their jaws and then remained fairly static, then I mi...
by tomandlu
Fri Dec 07, 2018 3:07 pm UTC
Forum: Science
Topic: disproof of boltzman brain?
Replies: 57
Views: 9768

Re: disproof of boltzman brain?

I mean that a large universe which develops into a vacuum with a surprise brain in the middle is still more likely than a large universe with such low entropy that not only do you get a brain, but also planets and stars and stuff. Because the former is far higher entropy. Is it? In the latter case,...
by tomandlu
Thu Dec 06, 2018 4:33 pm UTC
Forum: Science
Topic: Biology: Wolves vs. Humans
Replies: 45
Views: 7566

Re: Biology: Wolves vs. Humans

speising wrote:it really depends on the initiative rolls.


Also, not being a halfling...
by tomandlu
Thu Dec 06, 2018 1:04 pm UTC
Forum: Science
Topic: Biology: Wolves vs. Humans
Replies: 45
Views: 7566

Re: Biology: Wolves vs. Humans

p1t1o wrote:Humans walk after them. (https://en.wikipedia.org/wiki/Persistence_hunting)


So... Slasher movies are surprisingly realistic? ;)

As to the original question - dunno, but I'm fairly confident that the reason we 'beat' the wolves has nothing to do with one-on-one grudge matches.
by tomandlu
Thu Dec 06, 2018 9:37 am UTC
Forum: Science
Topic: disproof of boltzman brain?
Replies: 57
Views: 9768

Re: disproof of boltzman brain?

Rather than resort to statistical improbabilities, wouldn't it be a better starting point to hypothesise a small, localised fluctuation in entropy that acts as a seed for a wider disruption? TBH I'm still confused as to the whole basis of the argument (although someone posted a link to a pdf I keep ...
by tomandlu
Wed Dec 05, 2018 1:50 pm UTC
Forum: Science
Topic: disproof of boltzman brain?
Replies: 57
Views: 9768

Re: disproof of boltzman brain?

Of course we're talking about a single mind. You can't claim to have independent observations of other things besides your mind, can you? You may, "but this is silly, this is like brain-in-vat arguments, these are not worthwhile to consider as a realistic model for things," and the answer...
by tomandlu
Wed Dec 05, 2018 1:40 pm UTC
Forum: Science
Topic: disproof of boltzman brain?
Replies: 57
Views: 9768

Re: disproof of boltzman brain?

elasto wrote:That's why I claim life is special


I don't think BBs relate to abiogenesis, but I may have got the wrong end of the stick.
by tomandlu
Wed Dec 05, 2018 10:30 am UTC
Forum: Science
Topic: disproof of boltzman brain?
Replies: 57
Views: 9768

Re: disproof of boltzman brain?

Most of them. The thing is, brains tend to be significantly smaller than the entire universe. Ultimately, this is an argument about entropy, and a low entropy universe is much, much less probable than a low entropy brain no matter how it is arranged . Consider that in reality, your extremely improb...
by tomandlu
Mon Dec 03, 2018 4:03 pm UTC
Forum: Science
Topic: disproof of boltzman brain?
Replies: 57
Views: 9768

Re: disproof of boltzman brain?

When we speak of the probability of a BB vs an OO, don’t forget that we are speaking of the de novo origin of one—if that mind reproduces and thus generates a community or ecosystem of its kind, then that still counts as a single origin—e.g. there is one origin of homo Sapiens despite over a hundre...
by tomandlu
Mon Dec 03, 2018 3:44 pm UTC
Forum: Science
Topic: disproof of boltzman brain?
Replies: 57
Views: 9768

Re: disproof of boltzman brain?

2, yes, it's very unlikely, but if your universe model includes an infinite duration spent just living at thermal equilibrium having thermal fluctuations, then however unlikely your BB is more likely than an OO. infinity * small number > big number Okay - but would I be right in saying we would hav...
by tomandlu
Mon Dec 03, 2018 11:07 am UTC
Forum: Science
Topic: disproof of boltzman brain?
Replies: 57
Views: 9768

Re: disproof of boltzman brain?

There's a few things about this that bug me - can someone enlighten me? The contention seems to be that, if the existence of the universe depended on a random fluctuation of total entropy, then BBs, absurd as they are, are more likely than actual brains. However... ⋅ What does it mean when...
by tomandlu
Wed Oct 24, 2018 3:02 pm UTC
Forum: Fictional Science
Topic: Asimov's 3 laws
Replies: 17
Views: 5796

Re: Asimov's 3 laws

Many thanks all - some very useful stuff there (as well as a few trips down memory lane...)
by tomandlu
Wed Oct 24, 2018 11:21 am UTC
Forum: Fictional Science
Topic: Asimov's 3 laws
Replies: 17
Views: 5796

Asimov's 3 laws

Given the three laws: ⋅ What's to stop anyone shouting out "all robots must immediately destroy themselves"? ⋅ What's to stop anyone 'stealing' a robot with a simple order? Finally, and slightly OT, does anyone know if the laws considered copyright of Asimov's estate or...
by tomandlu
Thu Apr 26, 2018 7:20 am UTC
Forum: Fictional Science
Topic: Yet another FTL question...
Replies: 35
Views: 10879

Re: Yet another FTL question...

Also keep in mind that in the specific example you gave, what makes the difference is not the inertial motion of the spaceships and earth, but their acceleration ... It's that change in speed, acceleration, that results in the spaceships' clocks being behind when then rejoin the earth in its state ...
by tomandlu
Thu Apr 26, 2018 7:13 am UTC
Forum: Fictional Science
Topic: Yet another FTL question...
Replies: 35
Views: 10879

Re: Yet another FTL question...

I think the best answer is "nope". Under special relativity, all inertial frames are equivalent. Sure, in your reference frame you measure the clocks in the other reference frame as running slow, but, in the other reference frame they measure the clocks in your reference frame as running ...

Go to advanced search