Posted on 11/23/2017 9:07:33 AM PST by EBH
It is a calculation based on assumptions. They assumed that there was no prior event that caused it’s current trajectory. Direct evidence would have been Actually seeing it in another galaxy, but as of right now that isn’t exactly possible.
Cheers,
“Almost certainly” is not direct evidence. If a bullet is buried in a tree we can calculate were it “May Have” come from, but a photo of the shooter would be “Direct Evidence”. In other words there may have been a prior collision that set it on it’s current course.
Cheers,
I have no idea what you're talking about.
When I was earning my B.S. in Physics (admittedly, a long time ago), I used to love "playing" with celestial mechanics.
This object had, at a certain position in space, a velocity greater than the Sun's escape velocity at that position. Apart from some unimaginable concatenation of events prior to that point in time (i.e., a series of extremely close swing-bys near the Gas / Ice Giants), that can only mean that the object was/is not in orbit around the Sun, but was/is rather on a hyperbolic trajectory.
It's really very simple reasoning.
Regards,
Scientists almost never expect to find "direct evidence."
Rather, several items of mutually-supporting indirect evidence are considered more than sufficient to work with.
Regards,
I am at the Ph.D. level and worked with Drs. Rosen ad Phillips, along with many others at HAC and Caltech/JP 1984 to 1992. My most fun project was the Galileo probe project.
Celestial Mechanics is theory that lays a foundation of ***understanding***. It’s important for understanding and for using as a foundation of modeling.
In applications and operations, all parameters or coefficients taken from theoretical equations become ***estimates***, and when they are time-dependent, they change with time. For example, pure Kepler equations are beautiful and effective under purely stable fixed conditions, but if there are any external perturbations, the predictive models become statistical models to account for such perturbations, for example leading to Monte Carlo estimated confidence geometry.
A specific example would be predicting the impact area on the Earth’s surface of say, the massive External Tank of the Space Shuttle. It is not possible to pinpoint the impact area precisely so a 95% confidence ellipse is estimated given the launch inputs. The algorithms to compute it work very well. But the basic model is a Kepler model which you may have studied in a physics book. When you take the next level to an operating real-time setting, the Kepler model needs a whole lot of massaging. But it’s a good starting point.
When calculating orbits of real objects in the planetary system, the same approach is taken to start with elementary models adding components to the equations to account for unknown effects. The modeling equations become statistical models. These unknown effects are modeled to minimize variation (2nd moment effects). So for example, the Sun’s unknown trajectory and the gravitational effects of other orbiting bodies are assumed to be reflected in these 2nd-moment data, and can oscillate over time as the object in focus is tracked. Changes in relative distances are plotted to 3D ‘banded’ trajectories referenced to the Sun. These banded trajectories are not lines or curves, they are more like tunnels where the object may be.
When the electronic sensors and pingers that track an object of interest are in operation, the data processing returns a ‘model’ of reality. Many assume incorrectly that what is viewed is reality, but it’s only a model of reality. The models are very accurate but sometimes models can be off, can break down due to limitations of the signal processing equipment. The young NASA engineers better know these limitations.
Tracking a natural object trajectory in the planetary system is different than say tracking the location of a Voyager satellite. The man-made satellite is designed to maintain or alter its trajectory to explore, to go where the controllers want it to go. The Voyager can escape the galaxy because it’s pulsed in a way that causes it to escape. A natural object may or may not escape. It may appear to have attained an escape velocity but other effects can alter that result over time. It may be that the object escapes, or it may be that other effects cause the object to change its trajectory. It could be the object follows an incredibly long orbit. Or it may be interstellar. The write-up and the reference to Nature do not pin down which it is.
I can’t tell you the seemingly countless times I found errors in modeling, in computational algorithms, in the interpretation of results. I have seen the faces of program managers grow anemic as they were shown errors that their programmers had checked dozens of times but had missed. In most cases, the actual errors were within the corrected error bounds giving the teams great relief. But in some cases, one in which I was involved, the program was reviewed for cancellation. The team I was on was feared as it should because review is necessary.
These youngsters at NASA are having fun calling out what appears to be a nice story. The nice story may be reality or may be fiction. We will have to wait and see.
I humbly bow to your superior intellect! (snicker!<)
No, sincerely - but I think that you are getting unnecessarily technical in your explanation, as well as being unnecessarily pessimistic.
Before continuing, let me express agreement with the accusation made earlier in this thread that newspaper journalists, of course, go for the juicier headline and are hence more than willing to obfuscate the facts to that end.
In short: The article could have easily presented some simple fact making it perfectly clear that - barring some unimaginably unlikely scenario (multiple perfectly choreographed fly-bys) - the object must be of interstellar origin.
A specific example would be predicting the impact area on the Earth’s surface of say, the massive External Tank of the Space Shuttle.
That's a poor example, depending as it does so heavily upon the influence of the Earth's atmosphere. In the case at hand (this putatively interstellar object) - unless it's a comet (which I'm willing to stipulate, but which you, for some reason, didn't care to come out and mention explicitly as a possible "deal-breaker" for the interstellar hypothesis) - simple Newtonian mechanics and Kepler's Laws should suffice, nicht wahr?
Again, I'm not a scientist and am not pretending to argue here with scientific rigor - just on a par with the usual level of discourse here at Free Republic.
My understanding (based on this sloppy article, which didn't bother to present the prima facie evidence I would have wished for and which I really believe might already be available) is that the object had, at a point in space where the escape velocity of the Sun was, say, "X," a velocity of "X + k," where "k" is a positive number.
Wouldn't you say that, in the context of a popular science article, and a Free Republic thread, it would then be permissible to assume that the object in question is indeed extra-solar?
Regards,
> “No, sincerely - but I think that you are getting unnecessarily technical in your explanation, as well as being unnecessarily pessimistic.”
If you knew what the denizens of NASA do on a daily basis, you would understand better. There’s a reason why they are under constant threat of the budget ax. In order to return them to prestige, they claim more funding is needed and grander missions. That is not what they need. They need harsh oversight in a course where the tough survivors are rewarded greatly, making it Olympian to even gain employment in the agency, the way it was once.
NASA like so many other agencies of the federal government is overrun by political correctness. You should be skeptical of anything and everything they publish and claim to produce. Call them on the carpet and put them to the test. If they can’t take the pressure, let them quit.
Exactly! So it should not be called Direct Evidence as though it was a Detective Show. Most likely the scientists did not put that way, only the writer.
Cheers,
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