The Naked Scientists
  • Login
  • Register
  • Podcasts
      • The Naked Scientists
      • eLife
      • Naked Genetics
      • Naked Astronomy
      • In short
      • Naked Neuroscience
      • Ask! The Naked Scientists
      • Question of the Week
      • Archive
      • Video
      • SUBSCRIBE to our Podcasts
  • Articles
      • Science News
      • Features
      • Interviews
      • Answers to Science Questions
  • Get Naked
      • Donate
      • Do an Experiment
      • Science Forum
      • Ask a Question
  • About
      • Meet the team
      • Our Sponsors
      • Site Map
      • Contact us

User menu

  • Login
  • Register
  • Home
  • Help
  • Search
  • Tags
  • Member Map
  • Recent Topics
  • Login
  • Register
  1. Naked Science Forum
  2. Profile of Halc
  3. Show Posts
  4. Messages
  • Profile Info
    • Summary
    • Show Stats
    • Show Posts
      • Messages
      • Topics
      • Attachments
      • Thanked Posts
      • Posts Thanked By User
    • Show User Topics
      • User Created
      • User Participated In

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

  • Messages
  • Topics
  • Attachments
  • Thanked Posts
  • Posts Thanked By User

Messages - Halc

Pages: 1 [2] 3 4 ... 111
21
New Theories / Re: If there was one Big Bang event, why not multiple big bangs?
« on: 14/05/2022 06:52:40 »
Quote from: Bogie_smiles on 13/05/2022 23:18:15
Would you mind posting a few words from your thoughts
For the most part, you seem to have gotten completely off track. None of your recent posts have been about multiple bangs or related theory. To be honest, I have little idea what you're currently proposing. You're just blogging random and mostly unrelated thoughts.

Quote
about how unique life is in the universe, given an infinity of time and space.
If life is of any probability greater than zero for any given star system, then given unlimited star systems, there must be life on an unlimited number of stars. Any other possibility is mathematically inconsistent.
This assumes infinite space (and thus infinite star systems), but not infinite time, since any given type of life is only good for a finite region of time: Too soon and there's too much violence and not time to develop stable life. Too late and entropy takes over and there's no energy left to support life. As it is, life has been on Earth about 4-5 billion years and all but the simplest life will be gone here in another billion. The planet will not support eukaryotic life soon, and that includes anything multicellular.

22
Physics, Astronomy & Cosmology / Re: Is this a paradox in general relativity?
« on: 14/05/2022 06:42:46 »
Quote from: Dimensional on 14/05/2022 06:08:03
At the higher of the 3 clocks/events is the nose of the ship according to an observer on the ground and so is the clock/event below it.
This sentence doesn't really parse for me, so hard to figure out what you're trying to say. There seem to be no clocks depicted in the 30 second clip you indicate. The vid around 6:45 shows a spacetime diagram with one event at the rear of the ship and one nose event (the lower one) for the 'ground' frame and another nose event (the upper right one) for the ship frame, each simultaneous with the rear event in their respective frames. Hence the 20m ship is contracted by a sixth in the ground frame. All pretty straight forward SR so far.
Perhaps the 'lower clock

Quote
Now my thought experiment is about what might happen if an object moves really fast in front of the nose of the ship where the lower clock/event is.
OK, at some point an object crosses in front of the ship.

Quote
To make the object appear in front of the nose almost instantaneously, we will say that it came from another spatial dimension z going into your screen.
Or y, since the diagram only shows the x axis. The vertical axis is t (ground frame).

Quote
If an interception between the contracted nose (the lower clock) and the object is possible in the scenario given, it would seem that there would be an interaction with the nose of the ship that will never happen with the nose of the ship in the future (the higher clock).
You're saying the object that crosses in front bumps the nose of the ship as it goes by, but not enough to damage anything. That's an objective event. It must occur in any frame. Perhaps it left a mark. In the ship frame at the time indicated in the video, the bump event you describe has already happened in the past and the mark on the nose is already there. The nose of the ship follows the nose worldline (the dotted green line) and is present at every event along that line. Likewise the tail follows the parallel dotted tail line. Those lines are straight because apparently the ship is not accelerating in this scenario.

23
Just Chat! / Re: A Short puzzle with dogs.
« on: 12/05/2022 15:27:49 »
Quote from: Eternal Student on 12/05/2022 15:12:17
you have reached a local minimum not necessarily a global minimum
OK, you wait until a flood occurs and the water reaches just to the straight line between dog and house.
If that's on the table, you might as well wait for the flood to get even worse and perhaps carry the house much closer to the dog, which isn't too far off from my 'riding the raft' idea.

24
Just Chat! / Re: A Short puzzle with dogs.
« on: 12/05/2022 15:01:04 »
Another physical solution:
Spoiler: show
Replace the river 'rod' with a mirror and shine a laser (a surveyors laser that leaves a line on the ground) from the dog to the reflection of the house

25
Just Chat! / Re: A Short puzzle with dogs.
« on: 12/05/2022 14:52:34 »
I'm still working on the circle problem, but have had almost no time to do so. It's coming.

Maybe the dog can shorten the effort by jumping on a board floating on the river, saving steps. I presume such complications are not part of the problem.
This problem has a physical solution:
Spoiler: show
Just put pegs in a board where the house and dog are, and a rod representing the river. Tie a string to the dog and the house looped around the rod and pull it tight. It will move to the shortest path, which momentarily touches the river 4/7th of the way, or ~43 m west of the house.


26
Just Chat! / Re: Too much faith in computers/A.I.?
« on: 10/05/2022 19:57:40 »
Quote from: Pseudoscience-is-malarkey on 10/05/2022 19:12:54
Picard: Computer, what is the predominant material in Dyson Spheres?
Computer: Hematite.
Picard: Thank you.

Here's the problem with that: no one ever seemes to ever ask the computer where it gets its facts.
I love how they still name it 'computer' instead of giving it a cute name like Alexa or something. But they don't for the same reason no naming of source of data is involved: It's a fictional show and naming the computer something cute would leave some viewers unaware that it is a futuristic machine being queried, and the data source is not listed since doing so would not add to the plot. Writing for a TV show is very different than an attempt to simulate real discourse on a ship with all the same technology.

BTW, we already have a computer that can answer most questions. OK, it's ability to parse out the actual question being asked is still quite crude, but the answers are most often there.

27
Physics, Astronomy & Cosmology / Re: Does charge contribute to mass?
« on: 02/05/2022 17:48:31 »
Quote from: Eternal Student on 02/05/2022 17:26:11
For example if two charges are in close proximity, then you can describe the energy as being stored "in" the separated charges.

Anyway, I'm once again interested in where this energy really is and how it behaves:
It seems not to be 'in' any particular place/object/field, similar to the discussion about the mass of an object increasing at higher altitudes. The energy of the rock/Earth system is up, along with the system mass, but that mass is added to the system, not necessarily the Earth, rock, both, or the gravitational field.
Similarly, a system of two stationary protons in close proximity (not too close) has more energy than the same situation with greater separation, but it is probably a mistake to say that energy is in the protons or the field or whatever.

Quote
Hence, the main question:   Does charge contribute to mass?
System mass, not field energy or particle energy. Is charge of one particle 'energy'? Only way I can get energy from that is to introduce a 2nd particle, also charged, at which point the energy is a function of their separation.


Didn't yet read the spoiler. Your 'rubbed balloon system' charged with the 1800-1 arguably has more mass because all those extra electrons have been brought into proximity to each other, which is energy that can be harvested. It took work to put them there.

28
General Science / Re: Is 2 really prime? If so, why isn't 1?
« on: 01/05/2022 16:15:12 »
Your definition of a prime (in the OP) includes 1, but the definition asks for 'divisible by 1 and itself' and 1 is not a divisor of 1 in addition to the first 1. That's pretty shaky, but every integer > 1 can be factored into exactly one set of primes, and this would not be true if 1 was a prime. So 6 could be factored into 2,3 or 1,1,1,2,3 and the list goes on.

As for your geometry example just now, besides leaving 2 off the list, your definition as worded doesn't work as worded.
"regular polygons with n sides that can only be divided into n identical portions by connecting vertices to the center"
Take your hexagon. There is only one figure below it that divides it into 6 portions. The others are not divided into 6 so don't count. You might say "regular polygons with n sides that can only be divided into identical portions by connecting vertices to one common additional point".  The mention of the center is unnecessary since I don't see a way to do it without picking that point.  The "one common" part seems necessary since I can happily divide any regular polygon into many identical portions. The pentagon for instance can be slice up into 20 identical shapes, but only with the addition of more than one new point where the lines intersect.

Another possible wording:
"Any n>4 is not prime if a regular n-sided polygon can be divided into m identical portions, with 2 < m < n". Given that wording, my dividing the pentagon into 20 shapes doesn't disqualify it as being prime, and even counting mirror images as identical doesn't trip up the definition.

29
Question of the Week / MOVED: indefinite integral
« on: 27/04/2022 12:57:04 »
This topic has been moved to Just Chat!.

https://www.thenakedscientists.com/forum/index.php?topic=84643.0

30
Question of the Week / Re: QotW 22.04.25 Does a phone battery weigh more after charging it?
« on: 26/04/2022 04:15:14 »
Quote from: Tibor Molnar on 26/04/2022 01:53:30
Is it correct to say, then, that kinetic energy is somehow "local", i.e., attributable to some object
Under Galilean/Special relativity, KE of an object is a relation with an inertial reference frame. The object is stationary in one frame and has zero KE, but it is moving relative to another frame. This is true regardless of whether the measurement is local or not. It is position invariant. So the object's relativistic mass is frame dependent, but its proper mass is invariant.

Not so when gravitational potential is involved.  A 1 kg mass will still have a proper mass of exactly 1 kg measured locally, but if the measurement is not local, it changes.  Suppose we have an observer on the surface of a non-spinning Earth, and another way up on a tower above the first observer.  Between them a 1 kg mass goes by horizontally at say 100 km/sec as measured by an observer at the altitude of the moving mass. They'll measure different KE.  From below, the mass is moving faster than 100 km/sec and even a stationary object has a higher relativistic mass than a kg sitting right next to him.  From above, the opposite is true.
Just like in special relativity where relativistic mass is frame dependent and not attributed to (a property of) the object itself. Relative to an observer that stays with the object, it has neither kinetic nor potential energy relative to him and thus still masses exactly 1 kg.

Quote
whereas potential energy is somehow "global", attributable to a whole system?
A ES explained far better, PE is a attributed to a system, so raising a rock to a top floor adds energy to the Earth/rock system and thus the mass of that system, but it is a mistake to attribute that new mass to just the rock or the Earth. My first reply made it sound otherwise, and ES corrected that.

31
Question of the Week / Re: QotW 22.04.25 Does a phone battery weigh more after charging it?
« on: 25/04/2022 22:49:03 »
Quote from: Eternal Student on 25/04/2022 18:03:55
Gravitational potential energy is not well defined in General Relativity.   We've had some discussion about this before.
Agreed, and I have to remember that when making seeming blanket statements like I did. Mass is frame dependent, and so is kinetic and potential energy. Mass of a rising brick goes up as 'measured' by some device at some constant potential, but if you were to measure the local mass of the brick, it doesn't change a hoot at different altitudes. This makes me wonder how one might go about measuring the mass of something that isn't local. I can't think of an obvious way to do it.  You can measure its weight with help of strings and such, but that isn't mass.

Quote
LATE EDITING:  An even easier way to phrase this:  A 1 Kg brick still masses 1 Kg as determined by its resistance to an applied force OR by its ability to act as a source of gravitation regardless of high high up in the air you take it.
That acceleration due to a force is again frame dependent. It will be measured differently depending on the potential at which the measurement is taken. Hence it being an interesting problem.

Thanks for the correction ES.

32
Question of the Week / Re: QotW 22.04.25 Does a phone battery weigh more after charging it?
« on: 25/04/2022 15:06:34 »
First of all, welcome to the forum. May it not be your last visit.

Quote from: Tibor Molnar on 25/04/2022 14:19:07
PS: Do you know a reference that addresses this specific point?
I hadn't used one for the above reply, but a quick search turned up this:
https://physics.stackexchange.com/questions/34421/does-the-mass-of-a-battery-change-when-charged-discharged
which contains a much more quantified answer. They calculated that an electric car gains about half a microgram when charged from empty to full. A phone would gain much less of course.

33
Plant Sciences, Zoology & Evolution / Re: Which came first? The chicken or the egg?
« on: 25/04/2022 12:49:00 »
Rigid eggs were around since perhaps the Cretaceous, long before there were chickens, so any designated 'first chicken' most assuredly came from an egg laid by its mother that was not a chicken by definition.

One might alternatively ask what came first, the chicken or the chicken egg, which simply comes down to how one defines a 'chicken egg'. Is it an egg laid by a chicken, or is it an egg containing a chicken? The answer depends on this definition, but is obvious either way.

34
Question of the Week / Re: QotW 22.04.25 Does a phone battery weigh more after charging it?
« on: 25/04/2022 12:37:02 »
Quote from: Tibor Molnar
We understand that energy has mass (E=mc^2), but what about potential energy? Does it also have mass? For example, if I charge up the battery in my phone, does my phone become (fractionally) heavier?"
E=mc˛ appies to all energy, so all else being equal (no change in fingerprints for instance), the phone masses a tiny bit more after being charged. It also masses more if you move it from downstairs to upstairs since it gains potential energy that way, but it probably weighs less upstairs since it is further from Earth. So increased mass doesn't necessarily imply increased weight.



35
New Theories / Re: If there was one Big Bang event, why not multiple big bangs?
« on: 23/04/2022 14:01:12 »
Quote from: Kryptid on 23/04/2022 05:47:58
It looks like Dave is turning this into a duplicate topic of his Big Bang threads. Would that count as derailment here?
Dave is trolling in another person's blog. He obviously has no desire to learn anything since answers to all these misconceptions have repeatedly been given.

36
Technology / Re: Water Resources Assignment Help
« on: 23/04/2022 13:40:22 »
I suspect he's offering to give the help. There was no hint of a question in the OP.

37
That CAN'T be true! / Re: Does the IVO thruster violate Newton's third law?
« on: 21/04/2022 18:21:51 »
Quote from: chiralSPO on 21/04/2022 17:43:12
A brief google search brings these up:
Mine got me here
https://www.forbes.com/sites/briankoberlein/2017/02/15/quantized-inertia-dark-matter-the-emdrive-and-how-to-do-science-wrong/?sh=19902960675f

38
General Science / Re: Are space and time just two sides of the same coin?
« on: 20/04/2022 16:41:51 »
Quote from: Seafire on 20/04/2022 08:47:07
If it seems unimaginable any two object can exists at a different time then you must reject GR
Nonsense. All enduring objects (anything lasting for more than an instant) exists at different times, else time/velocity/force etc. all would have no meaning. This is not unique to GR

Quote
for in GR the speed of light or event horizon can stop your introduced flow of time idea for one object on Tuesday but then stop another object on Wednesday.
Time isn't something that flows in GR. Time doesn't stop at an event horizon. An object falling into say a black hole has a very specific time (a reading on its clock, Tuesday say) when it crosses the event horizon. A second object is quite free to do the same on Wednesday. Neither object notices anything locally funny like physics working differently, clocks stopping, or anything like that.

Quote
These two objects are therefore frozen at two different points along the imaginary flowing timeline that you introduced
It seems you are the one trying to introduce said imaginary flowing something into a theory that doesn't posit it. The words 'flow' and 'timeline' do not appear in this topic until you introduce them.

You're using second-person language here, but are not replying to any specific post, so it is unclear who you think is introducing these things you appear to find contradictory. I mean, there are alternative theories which posit time as something that flows, which yes, does discard all of GR, but even these don't have time stopping anywhere. It marches on at some fixed (and totally unmeasurable) rate everywhere.

39
Just Chat! / Re: Are The Naked Scientists Listeners open to interviews?
« on: 19/04/2022 15:55:27 »
Quote from: glesphlep on 19/04/2022 15:25:14
I would consider people that are willing to do an audio interview (via Zoom or the preferred platform), as well as using questions and answers in written form.
This would work.  Audio can be done via zoom or something like discord, all keeping identity anonymous if that is desired.
Written questions can be done right in a topic thread, but there's a danger there of people answering differently with public answers than with private ones. The site PM system can be used to keep answers private from other members, and I don't think this breaks the rules against using PM to 'spam members'.

Without hearing the questions, I'm more of a reader than a listener and have always had trouble absorbing information from audio instead of texts/diagrams. It's been a long time since I've heard a science educational program on the radio. I've seen some great-courses science lectures and have been vastly disappointed in them. Such an opportunity for good visual aids, but no, they just park the camera on a talking head.

40
General Science / Re: Are space and time just two sides of the same coin?
« on: 19/04/2022 05:49:02 »
Quote from: Seafire on 19/04/2022 05:34:03
Hi everyone, I have a question about space-time that I hope someone can explain properly.

Are space and time just two sides of the same coin?
In the space-time model, space and time are different dimensions of the same stuff, so they share geometric properties, such as ontology.

Quote
If this is true and we live in a universe made up of different spaces then it must also be true that we live in a universe made up of different times
Don't know what you mean by this, but it appears to not follow. Yes, there are different spaces: here is not the same location as there. Tuesday is a different time than Wednesday, but these are all true even in a model of separate space and time, so it doesn't follow from a spacetime model.

Quote
does every point in the universe exist at a different time?
Points in spacetime are called events, and events with spacelike separation can be simultaneous relative to some coordinate systems, and not simultaneous relative to others. There is no objective ordering of events with spacelike separation, but there is objective (not frame dependent) ordering of events with light-like or time-like separation.

Pages: 1 [2] 3 4 ... 111
  • SMF 2.0.15 | SMF © 2017, Simple Machines
    Privacy Policy
    SMFAds for Free Forums
  • Naked Science Forum ©

Page created in 0.065 seconds with 66 queries.

  • Podcasts
  • Articles
  • Get Naked
  • About
  • Contact us
  • Advertise
  • Privacy Policy
  • Subscribe to newsletter
  • We love feedback

Follow us

cambridge_logo_footer.png

©The Naked Scientists® 2000–2017 | The Naked Scientists® and Naked Science® are registered trademarks created by Dr Chris Smith. Information presented on this website is the opinion of the individual contributors and does not reflect the general views of the administrators, editors, moderators, sponsors, Cambridge University or the public at large.