Silvestru

10 minutes ago, Strange said:

I think that is a good point. We don't know what dark matter is (or even if it is matter). If it is some form of matter, it would seem that would have to be something outside the current standard model. And if it isn't some form of matter, then it is new physics by definition.

I always knew you are a MOND person!

Ok, back to dark matter. You propose to qualify it as "largely unknown". Yet it is consistent with our observations. There is a whole section about it on the wiki page.

https://en.wikipedia.org/wiki/Dark_matter#Observational_evidence

It's still hypothetical just because we don't know what it's made of because it does not interact(doesn't seem to) with EM Radiation. But Galaxies are not flying apart from each other. So why is that? Some unseen matter is "holding them together".  We call this "dark matter". Which part of this thinking process would you change? I would agree with you only that the name confuses the weak of mind and I have had heated discussions trying to explain that this is not evil energy.

3 minutes ago, Danijel Gorupec said:

Sorry, my reaction was only because of language use (from Zapatos side). Using the term 'not fully understood' seemed to me like an overstatement... I think that scientists should be brutally honest also when evaluating own accomplishments. Anything else can backfire, imo.

So I propose not to use the 'not fully understood' qualification when talking about dark mater and dark energy. A better term, imo, would be 'largely unknown' or similar.

I would suggest to use the 'not fully understood' qualification only if you strongly believe that explaining a phenomenon will not introduce any new physics (that it can be explained only by known physics). I don't think that our dark mater and dark energy understanding is there yet.

So by this logic, we would describe electromagnetism as "not fully understood"? It ticks on all your criteria. What about a more specific phenomena like lightning. 

Should we describe lightning as not fully understood?

What about magnetism. If my cousin asks me why a magnet attracts a screw should I say that this is not fully understood as well?

On 29/10/2018 at 1:48 PM, Endercreeper01 said:

If you know what a NDE is, you would know how vivid they are.

I have no doubt they are vivid. You know what else is? Mushrooms. 
No one is claiming that they are a portal to another world. Actually some might but anyway the point is that the mind plays tricks.

25 minutes ago, Danijel Gorupec said:

Not yet fully understood? Sorry, but it is closer to 'we have no idea'. Do you disagree, do you feel that science must be defended by not admitting this, or did you just made a language-use mistake?

What do you mean admit? who do you feel that anyone owes you anything? Do you have a better model to explain why galaxies don't fly apart from each other? I am waiting

4 minutes ago, DrP said:

I always thought that it was knowledge. Science - the word, actually means 'knowledge' I always thought  -  that is what they taught us back in school anyway. The knowledge you have can be updated as more information is revealed about a system. As for 'absolute truth' - how could anyone ever know what they believed was absolutely true. You always have that unproven - 'what if' behind you.

I agree but that is not how the OP has defined knowledge. He has defined it as "justified true belief"

I am contesting the modern use of this definition.

I am also contesting the word "truth" in the OP's context as in science this implies that there is 100% chance of something being the case. 

That is not what science is about.

If you can keep your definition of knowledge about science by accepting that science is in constant flux and that it never "proves" anything 100% then yeah. 

2 hours ago, Reg Prescott said:

Knowledge, as traditionally defined since antiquity, is justified true belief

It definitely is not. I would argue that with no prior knowledge or education, it would be "justified" to think that the sun and moon are orbiting the earth and that we are in the centre base don primitive observation. People who have questioned this and have made further research have come to the conclusion that it is not true.

2 hours ago, Reg Prescott said:

(3) is self-explanatory. One cannot have knowledge of that which is untrue. You might believe that Paris is the capital of Italy; you may even have good reasons for believing this; nevertheless, you cannot know that it is so. For the simple reason that it is not so.

Ok I will play. How do you know that Paris is not the capital of Italy? Based on what?

2 hours ago, Reg Prescott said:

I'm fairly sure the majority of our members would be unwilling to accept.

100% with you on this one. 

2 hours ago, Reg Prescott said:

How much knowledge has science produced about the cosmos, the stars, the galaxies, the planets?

Scientists have "produced" observations and models and the successful models match what was observed. This is not knowledge or truth. 
We discover new things every day that have influence on what we previously thought is how something works. No scientist "believes" anything in the faith sense.

That has to do with Religion.

2 hours ago, Reg Prescott said:

One must believe the proposition

One must be open to the possibility of the proposition. But not even that....

2 hours ago, Reg Prescott said:

(2) One must have sufficient justification for believing that proposition

Sufficient observational data, peer review and testing 

2 hours ago, Reg Prescott said:

(3) The proposition must be true

The proposition currently describes and is in line with what we observe. This could change in the future.

3 minutes ago, Ten oz said:

Humans have never been able to generate an experiment where we have sent anything out and measured over a galaxy sized distance. We measure on our end and are able to calculate what we receive but point of origin values are often assumed. By assumed I am not implying without solid reason. We are discussing  a simulated universe though.

I also used to make confusing statements in the physics section and then explain half way that I was actually talking about a simulated universe and that they got me all wrong.

4 minutes ago, Ten oz said:

To know for sure we have to get out. If you and I are simulations who is to say MACS0647 (furthest known Galaxy) isn't just a signal within the simulations program mimicking a distance Galaxy which isn't actually there?  

This is a straw-man argument.  If we live in a simulation then I could be giving you a back-rub and still could be "just a signal within the simulations program mimicking a polar bear"

Also if you would go to MACS0647 and send me a tweet it would make no difference in your argument. We detected it that means we know where it was billions of years ago. In relation to how long ago the photons we receive were emitted and the expansion of the universe and other different factors. But we are aware of these factors.
So explain please how would we better measure c if you were in MACS0647.

24 minutes ago, Ten oz said:

Doubt is the wrong word. Something is known till it is known. We can accept certian concepts as highly probable And still concede they are known for sure. 

• Nothing is taken for granted in physics but when measuring a value in many different ways by many different parties and that value is consistent with the model .... actually it's not even about GR... we just measured c many times.
• Second, how would a colony in a different galaxy help convince you of c? 

1 hour ago, Ten oz said:

Models aside I think the real tests of speed, gravity, and so on will be done when human colonies are physically separated by larger distances than we have yet achieved.

This is what I don't get.

Maybe you prefer a funny gizmodo argument .(if this is what it takes) 
 

Quote

The speed of light in a vacuum stands at “exactly 299,792,458 metres per second“. The reason today we can put an exact figure on it is because the speed of light in a vacuum is a universal constant that has been measured with lasers; and when an experiment involves lasers, it's hard to argue with the results.

Lasers Oz...

10 minutes ago, Ten oz said:

No, not in a vacuum but between galaxies. We have models which can predict this but predictions do still need to be proved. 

I really don't understand what you mean. Do you doubt the value of c or you think it is not constant and could possible "slow down" during longer travel?

We have so many methods to measure c:

• Astronomical measurements
• Cavity resonance
• Interferometry

We can explain any "delays" from our colony by gravitational lensing maybe? There are also other factors like redshit, blueshift but we are able to explain these factors. I really don't know what you are hinting at   What would "between galaxies" change?

Hello forum,

I was thinking about gravitational lensing and was curious if it affects gravitational waves in the same time. We have just recently detected gravitational waves by LIGO but if there would be a neutron star crash at a large distance that would hypothetically emit photons and gravitational waves at the exact same time, would we "receive" them here on earth in the exact same time despite any "deflection" to the light (and gravitational waves?) caused by a massive object? 

If yes, are we using this effect to confirm LIGO results?

"Photons of light are not technically affected by large gravitational fields; instead space and time itself become distorted around incredibly massive objects and the light simply follows this distorted curvature of space."

32 minutes ago, Ten oz said:

Models aside I think the real tests of speed, gravity, and so on will be done when human colonies are physically separated by larger distances than we have yet achieved.

What do you mean models? There is concrete observational evidence for both. We don't need a colony in another galaxy to calculate the speed of photons in a vacuum. 

But I feel this is a bit off topic here.

14 minutes ago, Ten oz said:

Identifying artificial, designed, or otherwise imposed limits would be a clue. 

Hmm like how the speed of massless particles in a vacuum is always c?  Also gravitational waves. Also EMR.... suspicious 

1 minute ago, Theredbarron said:

Why is it called space time is the question. not what it is. 

you cant answer that can you?

Dude, even I answered it in my tortilla post. 3 spatial dimensions + 1 temporal one.

space + time= "space time"^TM

4 minutes ago, Theredbarron said:

Why is it called space time wrap and not existence?

Because of the juicy sauce that ties all 3 dimensions of space with a soft time tortilla dimension.

13 minutes ago, Theredbarron said:

existence is occupied by all.

13 minutes ago, Theredbarron said:

Existence is all.

13 minutes ago, Theredbarron said:

Time is ours.

You sound like my Yoga teacher. I have a bad back so I have to cope with the "woo" in the Yoga class but what are you trying to say?
Are you trying to say time is cyclical? What are your sources? Ok maybe I went to far with the sources request. Can you please expand instead?

19 minutes ago, Theredbarron said:

A defense system in place before an offensive happens is predicting the future.

Not really. I compared you to my nutty Yoga instructor so I am setting up a defensive brownie in place to cope with the potential offensive from you that might make me sad.
Unfortunately it's not seeing into the future. 

1 hour ago, Ten oz said:

The system isn't fair. It is common for Democrats to win more votes and still lose. Democrats already have the more popular candidates, evidence being they get more votes, and it isn't enough. It is easy to toss around equivalencies and what not but all that does is diminish what is a real problem. Can you provide an example on democrat based voter suppression or Republicans losing despite winning more votes? Below are examples of it for Republicans. II don't see how it is "way too much" complaining if it's true. 

You are 100% right Ten oz and I stand corrected.  I was just airing my ignorant uneducated opinion. Unfortunately that describes a big chunk of the american voters. (especially republican according to the below poll).

http://www.people-press.org/2018/03/20/1-trends-in-party-affiliation-among-demographic-groups/

I agree that the system isn't fair but I also see that it's easier to "trick" and distract the american public.  Of course the US is in the global media spotlight but I really don't hear so many dirty tactic news pieces from other "free" countries. I don't imagine the examples that you gave happening in Norway, Sweden etc. Or if they happen there are consequences. Of course it's just my opinion.

16 minutes ago, J.C.MacSwell said:

I doubt they get "crushed", but if they do it is probably more from shooting themselves in the foot than Trump shooting his mouth off.

Gloves come off. I was waiting until someone would throw the first stone  But I agree. Democrats tend to demonise the other party recently and to victimise themselves way too much. 
Democrats should construct and grow a real good candidate for the next election. Someone who really has a shot. Unfortunately following the current trends, the winning choices that come to mind are Oprah, Eminem or The Rock . 

You need a famous entertainer to beat a reality TV show star. Simple as rock paper scissors.

3 hours ago, Moontanman said:

It's interesting that the fish with the largest brain to body ratio, larger than the brain to body ratio of humans, has electrical sonar, communicates via electrical impulses, engages in complex social behaviors, navigates its environment, detects prey, is blind, and does this as neatly and precisely as any sighted animal...  

Which fish is that Moon?

I am confused if you are calling the whale a fish or you are talking about Manta Rays, Sharks or elephantfish. (all of them have very high brain to body mass ratio)

58 minutes ago, Strange said:

Good summary (with a neat diagram) here: https://en.wikipedia.org/wiki/Spacetime#Privileged_character_of_3+1_spacetime

Thanks Strange!  I love the conclusion after the entire chapter:

Quote

Hence anthropic and other arguments rule out all cases except N = 3 and T = 1, which happens to describe the world around us.

6 minutes ago, Strange said:

Although there is evidence that a universe can only have 3 spatial and 1 time dimensions; it seems any other combination is unstable/impossible.

Can you please provide some source for this?  I am not contradicting, I just want to read further on this topic.
Why couldn't there be another temporal dimension? (Of course this discussion is moving dangerously to the limits of physical evidence so please tread lightly )

I thought that "Most physical laws are already written in a dimension-free form."

3 minutes ago, geordief said:

So c is fundamentally  a ratio rather than a simple constant?

Not sure I understand. It is not a mathematical constant it's a physical one. But also my response is in relation tho this new Universe. If you invent a universe it can have any physical laws you desire . c could be slower and our observable universe would be much smaller. Biochemistry would also be affected of course. Basically everything.

8 minutes ago, geordief said:

Referring back to Brian Cox's "musings "would it be conceivable for a fundamental ratio like that between distance and time to be different in another universe?

That "universe" would function very differently from ours. Even this slight change in c would have drastic effects on all particles.

I mean if c was 1 mm/s faster/slower.

Why DNA manipulation? Why not just cut the fore-arm and stick a whip in there. Army of darkness style.

Also: what are you talking about? That's the most random question I ever heard. Did you imagine that there is a whip gene? And you get it into your bloodstream and become whip-man?