Planet Earth was discovered by interstellar travel capable civilizations long before conditions became hospitable for plant and animal life as we have today. Ability to travel between stars and reach specific destinations brings along a computing ability we can only imagine, advanced as we believe data control has currently become on Earth.
Observation of stars is something humans have already; what remains for mankind to discover are speeds beyond dimensions we perceive, for visible light and within the human detectable spectrum, such as ultraviolet, and gamma rays, x-rays and others. Visible light from a distant star we can see is not the only light it emits, which is also not limited to the 300,000 kilometers per second we believe is the ultimate possible velocity.
Inside the dimensionality of the human Earth environment, the limits we know certainly do apply. Think of a fired bullet; it cannot be seen by a human eye but the evidence of its travel and impact are unmistakable. Only recently in human photography has the ability been developed to capture one in flight. We know light exists primarily because we see it with eye organs designed to detect it.
Because we do not detect light photon movement beyond the speed limit of our dimensionality - 186 or 300 mi/km per second - we cannot detect physical things vibrating above ranges we're able to perceive, just as human hearing cannot what many animals easily hear.
Objects vibrating at frequencies above ranges we inhabit also emit or reflect light at velocities higher than our perceived limit. This is not an absolute clean break; many humans see things which exist outside the usual levels we inhabit, calling them apparitions, ghosts, auras and spirits.
This strays into dimensionality, human existence and the illusion of time. I'll unpack the two subjects in reverse, as a foundation to explaining how alien extraterrestrials observe Earth.
Time on Earth involves the rising and setting sun, or the daylight hours. Nighttime follows and the cycle repeats. We number each one and construct graphs called calendars. The moment Earth's atmosphere is left behind, time as perceived on the surface ceases to matter. This does not mean there is no sequence of events; it means they are not marked, recorded and displayed on the human calendar timeline.
Dimensions are ranges of existence. In school many of us learn the basics of geometry - the word means the measurement of Earth - which involves height, width and depth; dimensions. The measurements taken together allow size calculation but the dimensions also measure, thus define, borders and edges of physical objects, including human bodies.
As the dimensions, edges are measured for object after object, common rules emerge, applying to everything; laws of physics. How physical forces affect objects requires measurement of force and object.
We're good at it for some objects and physical forces, but have not traditionally recognized them outside the five human senses before measurement was possible, such as magnetism and nuclear radiation.
Human existence and dimensionality of our environments are deemed to be the limits; gravity, speed of light, wind resistance, material hardness and so on. It isn't possible to slow light down or make it go faster than it already does, right? This is an example of human dimensionality and limits.
Alien extraterrestrials who visit Earth are not constrained by our time passage, their bodies not matched or even affected by cycles of Earth rotations. They do not become fatigued or sleepy along a schedules & patterns Earth life follows. Sunrises and sunsets affect them as a rotating tennis ball with a black spot in front of a flashlight might affects humans.
The importance here relates to predictions and dates. School semester schedules, jail time, contract expirations, meetings & appointments, to name but a few time important items of human life, train us to desire a date or range for event occurrence.
Accuracy of prediction rests as much on the expected date(s) as an event itself. Even when unfolding as forecast, occurrence several months before or after the expected moment converts an otherwise accurate prediction into random or dumb luck.
Alien extraterrestrial observations of Earth do not consider very much, if at all, whether Earth is on one side of the sun or the other; January or July matter the same or not at all. At any given moment on our planet's surface, two human dates are simultaneously in effect anyway. How insistent upon precise prediction dates or ranges of them, can or should we be? An airline passenger sleeping across the international date line can state with a straight and honest face the "wrong" date, after waking up.
Shooting a dart at a rotating beach ball can't expect one side or the other to be more likely hit, which as the passenger airline example demonstrates, can at least mean a different date. Does it mean much, if anything, to only hunt wild boar from the animal's left side?
Waiting for a beach ball, like waiting for Earth, to rotate a few or dozen more times while a better dart is chosen, can mean differences of days or weeks. This is an eternity, utter disappointment or confirmation of a skeptic's doubts to the HUMANS who expect a certain day or week to arrive. For an alien ET visitor, the sensation of a human month can be one week or day.
When limits of dimensions are exceeded, human time is bent, twisted, expanded or contracted. Instead of a dart or arrow, shoot at Earth with light; easy enough, we have lasers. If light moves faster than humans believe, the Earth surface effect is a slowing down by comparison. A seven or eight decade human life feels like a week's trip on the other side of the Pearly Gates, with all detail, experience and knowledge gained while travelling, intact.
Dimensionality changes time.
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Everything light touches on Earth, whether from house lamps, streetlights or the sun can be observed from great distance and immediately. Human physical laws say light speed is fixed at but if images are instantaneous, observing Earth from the moon would remove the 1½ second delay.
With alien extraterrestrial technology, visible light can be amplified and re-transmitted just as we do with microwave communication across Earth; it's no great shakes for our alien ET friends to watch what happens on Earth the way humans do from satellites now. Lest anybody not know, a credit card under clouds or sun, can be read easily by a human satellite. Let's hope our satellite folks are honest.
Alien ETs possess technology to observe Earth live, even better than humans can viedo ourselves, and re-send the live feed across hundreds to thousands of light years. All electromagnetic signals and even sounds we produce can be captured at virtually any distance in the galaxy, from Earth and instantaneously. Most interstellar travel capable extraterrestrials have this technology.
The beauty of dimensionality is that inside our tri-parameter perceptions, fourth dimension alien extraterrestrials - a redundant description, because all interstellar capable ETs can enter, or generally exist in and always use the fourth dimension - can slow down to our ranges and recapture any sound or electromagnetic signal we produce.
How? Because events are sequential, it's straightforward to identify the pattern of preceding and subsequent signals, to look for a unique one. The key is direction, again made simple by our alien ET friends; they use our calendar and determine the date WE HAVE attached. With that, they calculate back rotations and with the already known signal origin location on Earth's surface, precise positions of Earth and thus the signal directions become known.
Our alien ET friends can capture American Civil War President Abraham Lincoln's famous Gettysburg address and play a high fidelity sound recording, if asked and accepted. So few humans might even believe this possible that it will never happen without asking.
See how disclosure is developing? What's important, even if life & death important to us, can possibly hold zero meaning for our alien ET cousins.
Beyond the ability to go ahead of human viewed light and sound, aliens can largely avoid repeater stations because they've also discovered how light moves instantly across dimensions.
In the next range above us - the fourth dimension - it's nearly instant across galaxial distances, which fro our perspective can be compressed where physical limits, edges and measurements of them are different.
Light frequencies can be tuned like radio broadcasts, and as we do this we see color changes. Consider doing so to not change color but send live images across hundreds of thousand os light years, right now.
Human belief that this is possible will come after a demonstration, which is unlikely to distort human history. Once we accept, we'll be shown the way to develop the ability ourselves. We'll be given the clues to locating this buried treasure gift and get the chance to enjoy opening the technology and playing like scientist youngsters, provided we've advanced to where we don't use it for missile targeting.
Alien extraterrestrial visitors to Earth observe through cameras and telescopes, live and recorded. The can listen to all Earth sound and image broadcasts of any type, monitoring Earth since long before humans appeared a thousand centuries ago.
They can completely conceal their physical presence leaving us zero chance of detecting either objects or signal transmissions they send.