Moontanman

7 hours ago, swansont said:

Your scenario “If a time traveler went back in time and changed something, no matter his motivation, could we know?” requires that time travel be possible.

 

They are based on what physics has to say.

 

But there is no scientific basis for this, because it’s not based on science. You can propose whatever you want, but like most fiction, if you delve too deep Into detail you will find problems. How does a memory get erased? How do things broken in one timeline get repaired if they don’t get broken in the new one? 

 

But you can propose a different answer and have the same justification that that would be how it goes. 

An experiment, even a thought experiment, has to have a consistent outcome.

You've convinced me, a thought experiment has to be based in reality as we understand it or it's meaningless, I apologize to everyone for wasting their time. 

11 hours ago, swansont said:

Time travel is theoretically possible under specific conditions, but the kind of arbitrary time travel you describe is not.

I am not proposing that time travel is possible.

11 hours ago, swansont said:

Here’s a link from the other time travel thread describing what can and can’t happen with time travel

https://www.preposterousuniverse.com/blog/2009/05/14/rules-for-time-travelers/

Interesting concepts but I see them as being in no way any more or less rational that any other time travel concepts and no more or less arbitrary than any others I have read about. 

11 hours ago, swansont said:

I don’t see where I ridiculed you or suggested that there was deception. I critiqued your conjecture, and you’ve been here long enough to know to expect that. Getting feedback should allow you to improve your question. 

Ok then, I still say my thought experiment is valid and that my assertion is valid as well. Boiled down to its most basic. The only person who can know the timeline has changed is the time traveler. Everyone else is carried along in the time stream and the original time stream ceases to exist. 

Of course this is fictional, the very premise is fictional, but fictional premises can be used to figure out logical outcomes in even fictional scenarios. the idea of course opens up a huge can of worms but they are fictional worms and only have meaning in the context of the fictional thought experiment. 

6 hours ago, sethoflagos said:

You miss my point entirely.

A precambrian rabbit would predate anything we believe remotely capable of giving birth to the first rabbit by half a billion years. 'Our history' as we understand it supports a pretty clear picture of the growth of the tree of life supported by millions of well-documented data points with not one single notable exception.

If subterfuge and misidentification etc. could be ruled out, we are left having to explain the existence of a genuinely identified item not of its rightful time. For those seeking evidence of time travel, anachronistic artefacts like precambrian rabbits (or 1st Dynasty Tricorders etc) are precisely the sort of hard evidence they would be looking for. 

You miss my point entirely, if someone was at war with someone else their goal would be to change time to their benefit not plant rabbits in the Cambrian. While not impossible, planting rabbits in the cambrian might just be the ultimate weapon... but killing a key figure in history would, at first blush at least, seem to be the easiest way to change history. No need to lug around high tech objects with you. Simply knowing the where and when of the target would allow you to pretty much eliminate them at your leisure.   

5 hours ago, swansont said:

The thought experiment is underconstrained because it’s fictional. 

How can you be sure that people don’t turn bright plaid when they time travel?

Because they chose that to be the story line. It’s fiction.

How do you know the memory wouldn’t exist?

Why does this have to be true?

It’s just an assertion. There’s no science that backs this up. You could just as easily assert that we would know. We could get temporal headaches and crave chocolate milk.

Any thought experiment will not be useful if nonsensical parameters are injected into the scenario for no reason other than to disrespect the person trying to honestly understand what we can and cannot know... yes this ties into my famous obsession with certain mysteries. i am trying to understand what can and cannot be known under any or all circumstances. Since time travel is as technically possible as warp drive but also just as surely impossible in reality and this fact has never been used to ridicule anyone who comes up with a thought experiment about what the effects of a real warp drive would be on society. I may not have hit the nail on the head with my thought experiment but my effort was honest and in no way deceptive or meant to ridicule anyone.   

I would have expected help to make my question better not ridicule to make me look bad.    

14 hours ago, sethoflagos said:

To paraphrase JBS Haldane (albeit in a slightly different context)

 

If there were precambrian rabbits, that would be part of our history and we would not know that time travelers had transported rabbits to the precambrian. My point is that how would we know what is natural and what is the result of intentional time changes?  

12 hours ago, MigL said:

It is, actually, just that.

I agree, I am not trying to justify time travel, I am trying to do a thought experiment to see if we could be aware of time changes. 

11 hours ago, swansont said:

Once you’ve decided to violate physical law, lots of fictional scenarios become possible.

Obviously but that doesn't negate the thought experiment. 

I am not suggesting time travel wars are real I am saying that if they were there would be no way we could know. The idea of a time war taking place in the cambrian ignores the actual idea of war. We would not nuke DC to hurt the Russians, any actions by time warriors would take place in ways that maximized injury to the enemy while limiting any damage to the "home team". 

An episode of ST Enterprise comes to mind. They were in the middle of a Temporal War, without the help of the actual time warriors I can't see how anyone would be aware of changes in the timeline made in the past since they could not be aware of those changes due to the past changing the present. In the episode Aliens had helped NAZI Germany to win WW2, no one who wasn't outside the timeline had a clue any changes had been made.  

If someone went back in time to stop Hitler and succeeded how could we know? Our present would not exist and so no one would have any memory of the original timeline... we, as individuals, would probably not exist at all. 

In all fairness here there does need to be a major assumption here in addition to time travel being possible. The time travelers would have to carry their time machine with them and be immune to the time changes due to this "machine" 

I just remembered the TV show "Timeless" They had this premise, they could change time and avoid those changes themselves. 

So my assertion is that we could not detect any changes in the timeline and we would be blissfully unaware of any "time war" no matter how world shattering the time changes were.      

Lots of silly crap is asserted on various platforms online but one of the weirdest is the idea that there is currently a war being fought across time. Of course various bits of "evidence" is asserted but... Let us for a moment participate in a thought experiment. 

Let's say we want to know if a time war is being fought, how would/could we know? If a time traveler went back in time and changed something, no matter his motivation, could we know? Or, in my estimation most likely, would the time changes be completely undetectable by us, the equivalent of non combatants? 

If someone went back in time and changed history, imho, we would never know, no matter how violent or destructive the acts of the time traveler were in the past those acts would be part of our history and be seen by us as simply how history unfolded. Even if time was changed a 1000 times in one day we would simply see those changes as our history... completely undetectable as anything but the way things were and are. IMHO. 

A time war is not just nonsensical from what we know about time travel if it was actually happening it would be something we could never know of... your thoughts?    

14 hours ago, Fermer05 said:

The ebb and flow is the result of the rotation of the Earth and the gyres.

Tides are not formed along the entire coast of the seas and oceans, but only on those coasts where there is a high speed of currents.
And the higher the speed of currents along the coast, the higher the amplitude of the tidal wave.
On those coasts where the speed of currents is 0 km / h, the amplitude of the tides is also 0 meters.

The waters of the lakes, seas and oceans of the northern hemisphere rotate counterclockwise, and the waters of the southern hemisphere rotate clockwise, forming cyclonic gyres.
https://en.m.wikipedia.org/wiki/Ocean_gyre
And everything that rotates, including the cycles, has the property of a gyroscope - to maintain the vertical position of the axis in space, regardless of the rotation of the Earth.

If you look at the Earth from the side of the Sun, the gyres, rotating with the Earth, turn over twice a day, thanks to which the gyres precess (sway by 1-2 degrees) and reflect a tidal wave from themselves along the entire perimeter of the gyre.
https://goo.gl/images/M4SJq8 http://goo.gl/AM5g1s

The waters of the White Sea rotate counterclockwise, forming a huge gyroscope whirlwind, which precessing reflects the tidal wave along the entire perimeter of the White Sea. A similar pattern of tides is observed in all lakes, seas and oceans.
White Sea. http://rivermaps.ru/doc/beloe/beloe-3.htm
http://tapemark.narod.ru/more/22.png

The waters of the Mediterranean Sea rotate counterclockwise, forming tides 10–15 cm high. In the Gulf of Gabes, off the coast of Tunisia, the height of the tides reaches three meters, and sometimes more, and this is considered one of the mysteries of nature. But at the same time, the whirlpool rotates in the Gulf of Gabes, precessing reflecting an additional tidal wave. https://youtu.be/wlvkrRdYNZ0
The tidal wave in the Amazon River creates a huge planetary circulation with a diameter of several thousand km., Rotating between South America and North Africa, covering the mouth of the Amazon River.
The pattern of movement of the tidal wave along the perimeter of the North Atlantic planetary circulation (according to satellite data).
https://youtu.be/ZEhm_ONTQKc?si=Gf4x72tNzhh5tYT4

The length of the tidal wave depends on the diameter of the rotation.
The height of the tidal wave depends on the rotation speed of the rotation, the orbital velocity of the Earth and the time of the rotation of the rotation (12 hours).
A = V1 • V2 / t
Where, A is the amplitude of the tidal wave.
V1 is the rotation speed of the rotation.
V2 is the orbital velocity of the Earth.
t is the time of the rollover of the cycle (12 hours).
Table of tidal amplitude versus current velocity, on all coasts.
1 km / h - 1 meter.
5 km / h - 5 meter.
10 km / h - 10 meter.
15 km / h - 15 meter.
The amplitude of the tides also depends on the size of the cycle, the amount of water under the cycle, the distance from the coast to the cycle and on the direction of the current (north, south, west, east).
The currents that move along the equator reflect a tidal wave north and south twice a day.
And the currents that move along the meridian reflect a tidal wave west and east 1-2 times a day.
Applied time - from 0 to 12 hours occurs when an ebb wave runs into a tidal wave.
A simple experiment can be made if you rotate the globe around the axis and in orbit, entwined along the equator and meridian with a plastic hose in which the fluid moves.
By the height of the tides, you can determine the speed of the current along the coast, relying on the map of sea currents.

Cut and paste someone else's nonsense (Fermer1959) or are you spreading it around under different names? 

On 12/18/2023 at 8:33 AM, Luc Turpin said:

https://phys.org/news/2023-10-scientists-philosophers-nature-evolutionary-law.html

 

OK, I read the link and all i can say is... DUH! Change occurs over time, what part of that would lead anyone to believe that evolution is confined to the Earth? 

2 hours ago, exchemist said:

As this is the person who once tried to convince members of another forum that you can be strangled by your own thymus gland in cold weather, nothing is off the table. 😄

ROFLMAO!

So many jokes here I'll let you guys make them out! 

This song should be playing in every voting center in the country during the election! 

18 hours ago, Ken Fabian said:

Rather than exciting speculation about exotic super heavy elements in super dense asteroids what is needed is dull and ordinary astronomical observations to get more accurate estimates of their density. As well better observations of everything else that can be determined about them - which should be standard practice, to add to the inventory of known asteroids and their characteristics. Confirmation of unusual characteristics would give cause to investigate further, including with probes. If very unusual it would be very good cause.

But without that confirmation it is like an anomalous experimental result - worth finding out why but it seems much more likely to be mistake than breakthrough.

Yes, I have my doubts about a stable element at atomic number 164, in fact I was under the impression that the so called island of stability was supposed to be around element 124 and the stability was somewhat less than... stable. 

More important than simply speculating is getting an accurate measurement. However, the margin of error is so great on this one it makes you wonder how such a extreme error could be taken seriously at all. Even if the asteroid was 100% Osmium the density is far and away from anything you would expect from a reasonable measurement. A pure Iron Nickel asteroid should have a density of around 7.8 grams per CC  even a pure Osmium asteroid, 22.59 grams per CC, which is wildly unlikely, wouldn't come close to the claimed measurement of 75 grams per CC.

Lots of unknowns in science, various readings, findings, measurements that do not comport with reality was we think we know it. I think it's important to investigate these things when possible, remeasure when possible, but we shouldn't fall into the trap of assuming something is impossible because we can't explain it.  

Is there some other possibility which would make this measurement a bit closer to reality? 

Do super dense asteroids point to the possibility of heavy elements not found on Earth? 33 Polyhymnia is thought to be 3 times as dense as the densest element on the earth Osmium. Osmium is 22.59 grams per cubic centimeter with an atomic number of 76 but 33 Polyhymnia seems to be made of something close to three times as dense as Osmium. This would correspond to an element that has an atomic number of around 164. 

 https://earthsky.org/space/ultradense-asteroids-polyhymnia-cudos-superheavy

Quote

osmium, the densest stable element on the period table? Osmium has a density of 22.59 grams per centimeter cubed (g/cm³). Scientists think Polyhymnia has a density of around 75 g/cm³. So the team was looking for stable, superheavy, ultradense elements that could explain Polyhymnia’s suspected composition.

Their calculations confirmed the prediction that atoms with around 164 protons in their nuclei (elements with atomic numbers of around 164) were likely to be stable. They also found that a stable element with atomic number 164 would have a density between 36.0 and 68.4 g/cm³. While not a slam dunk, the range does approach the suspected density of Polyhymnia.

Should we be thinking of visiting this asteroid to see if we can obtain samples of this unknown element? 

I had a doctor with a sense of humor once, scared the living shit out of me with a cast saw. He was a catbird for sure. 

One of the most often sighted cryptids and or sea monsters is the sea serpent, sailors, for centuries, gace reports of giant sea monsters that were large enough to endanger their ships and other wise scare the bejesus out of otherwise brave men. Some of the examples were the giant squids, now days we know that giant squids exist, maybe not as big as reported but still big enough to be monsters. Sea Serpent sightings are now days thought to be the result of Oarfish being mistaken for Sea Serpents but there are sea serpents alive today, real snakes that live in the sea, one of which is reputed to grow to 9 feet long. But has there ever been a real giant sea serpent like the one of legend? 

Yes! Yes around 50 million years ago there is thought to have been a sea snake that could have been as long as 40 feet or more! Palaeophis colossaeus was this snake! From the description 

Quote

Abstract: Palaeophis maghrebianus belongs to the Palaeophiinae (Palaeophiidae). This snake subfamily is relatively poorly known, and it is mainly represented by disarticulated vertebrae and ribs and by a few vertebral segments. Its intracolumnar variability remains also poorly understood. The discovery of new isolated vertebrae and vertebral segments of Palaeophis maghrebianus in the Ypresian (Lower Eocene) Phosphates of Morocco enables us to provide a more detailed diagnosis of this species and to describe its intracolumnar variability. Moreover, the new material reveals that this species could reach gigantic size being, with Palaeophis colossaeus, one of the two longer palaeophiids. The microanatomical and histological analysis of some vertebrae illustrating diverse positions along the vertebral column reveals the presence of osteosclerosis, especially in the anterior and mid-precloacal regions. The occurrence of this osseous specialization implies a role in buoyancy and body trim control in this taxon, which is considered a shallow marine dweller based on its anatomical features and geological data. Palaeophis maghrebianus also displays a dense vascular network suggesting a growth speed, and thus a metabolic rate, much higher than in the biggest extant snakes.

With all the "cryptid" enthusiasm for Megalodon I am quite surprised this snake isn't being blamed for sea serpent sightings, possibly it's relatively new discovery or maybe it is still to obscure, for whatever reason it remains true that giant sea serpents once existed... and old time sailors reported seeing them. I doubt there was any real connection but it remains an interesting coincidence. 

Now, if we can just find one washed up on shore 😁

18 hours ago, martillo said:

I think in a long path of evolution from a swimming aquatic lifestyle to after walking land lifestyles and yet after flying air lifestyles. I could think in tyrannosaurus as an amphibious descendant of crocodiles adapting to the walking land lifestyle for instance. Of course several branches of descendants could be opened from crocodiles. Tyrannosaurus could be just one of them I think. Why not to think in such possibility? Seems a very natural one.

You can speculate anything you want but if you are going to tear down a complete evolutionary tree I think you need to find out a little about the evolutionary history of life on Earth. T-Rex was not a crocodile, T-Rex was a Dinosaur, both are archosaurs, but crocodiles are not Dinosaurs. The last common ancestor of both existed before there were either. 

1 hour ago, martillo said:

This is quite what I'm talking about:

(from a page of National geographic in Spanish I have just found: https://www.nationalgeographic.com.es/ciencia/unas-huellas-fosiles-encontradas-rioja-revelan-que-algunos-dinosaurios-podian-nadar_20929) 

This is a spinosaurus not a tyrannosaurus of course but well illustrates my point of view.

As you said this is a spinosaurus not a T-Rex, compare the two then get back to me. 

2 hours ago, martillo said:

From Wikipedia:

Deinosuchus: "Using more complete remains, it was estimated in 1999 that the size attained by specimens of Deinosuchus varied from 8 to 10 meters (26 to 33 ft) with weights from 2.5 to 5 metric tons (2.8 to 5.5 short tons).^[15]"

Tyrannosaurus: "The most complete specimen measures up to 12.3–12.4 m (40–41 ft) in length, but according to most modern estimates, Tyrannosaurus could have exceeded sizes of 12.4 m (41 ft) in length, 3.7–4 m (12–13 ft) in hip height, and 10 tonnes (9.8 long tons; 11 short tons) in mass."

In a fight of both I would surely bet on the T Rex!

And I think Tyrannosaurus could be well adapted to live in grass-flooded areas. Not immersed, I agree now, just leaning his so heavy body on the water and sliding on it pushed by his strong legs and feet. Yes, I can quite "see" them in that lifestyle of a total ape predator on those areas...

Size has little to do with this, a T-Rex in water is about as helpless to large water carnivore as an elephant is to a great white shark. Elephants can swim more than 30 miles and can stay in the water for many hours but they are not going to try and take habitat away from dugongs just because elephants are bigger. 

You are aware that a T-Rex is, metabolically, akin to birds (they even had feathers)... an endotherm that needs but lacks the traits that makes crocodiles such successful predators in their cool watery habitats. Crocodiles are endotherms, need far less food and can afford to waits for days and or weeks and months between feedings... right? Spinosaurus was a totally different animal, shaped more like a crocodile and only some were adapted to a watery habitat and even that is still debated. Spinosaurus has been redesigned so many times and at this time is considered to have been a quadruped adapted to a lifestyle very similar to the quadruped crocodiles while T-Rex was a biped with almost nonexistent front limbs.