Photons disappear
Flux falls as 1/d². From 10 pc to M51, the same source becomes about 7.4×10¹¹ times fainter.
Research futures · explicitly separated
Beyond Earth 2.0
From detection to distance, civilisation and contact. Here the project asks what physics permits, what future missions might test, and what remains speculation—without leaking those ideas into the candidate evidence.
OBSERVED FACT · PHYSICS-BASED CALCULATION · MISSION FORECAST · RESEARCH HYPOTHESIS · AUTHOR PERSPECTIVE
The data universe
Scale only matters when it answers a question
Gaia DR3 holds about 1.8 billion sources, while time-domain surveys can create trillions of measurements. Those numbers are not exoplanet counts. A scalable evidence system should push filters toward archives, partition by stable identity and time, preserve manifests, and materialise only question-specific products.
The priority is information: stellar parameters that change planet radii, injection experiments that identify selection, spectra that test atmospheres, and time series that can falsify a signal.
Negative feasibility is a result
An Earth in another galaxy is not a scaled-up nearby observation
Angles collapse
At 8.6 Mpc, one AU spans about 0.116 microarcseconds. Ideal 550 nm diffraction alone asks for a kilometre-scale baseline before contrast and crowding.
Confusion dominates
Ordinary stellar transits remain unresolved inside crowded galaxy pixels. Microlensing, pixel lensing and X-ray eclipses can reveal candidates without characterising an Earth twin.
Case study · unconfirmed candidate
M51-ULS-1b
A single Chandra X-ray eclipse motivated a Saturn-size planet interpretation around an X-ray binary roughly 8.6 Mpc away. It is an unconfirmed extragalactic candidate, not an Earth analogue; its long proposed orbit makes a repeat transit a decades-long wait.
Read the primary study →Interactive physics
Could we ever reach it?
Choose any distance. Earth-frame travel is d/v. Traveller time uses special-relativistic time dilation. Light marks the causal limit; a massive spacecraft cannot reach c.
1.301
parsecs
4.243
light-years
4.014e+13
kilometres
| Reference speed | Earth-frame years | Traveller years | Lorentz γ |
|---|---|---|---|
| Voyager-like | 74,829.86 | 74,829.86 | 1 |
| Parker reference | 6,660.25 | 6,660.25 | 1 |
| 0.01c | 424.33 | 424.31 | 1.0001 |
| 0.1c | 42.43 | 42.22 | 1.005 |
| 0.2c | 21.22 | 20.79 | 1.0206 |
| 0.5c | 8.49 | 7.35 | 1.1547 |
| 0.9c | 4.71 | 2.06 | 2.2942 |
| 0.99c | 4.29 | 0.6 | 7.0888 |
Cosmic conversation
Earth sendsTarget receives
4.24 yearsReply reaches Earth
8.49 years
4.24 yearsReply reaches Earth
8.49 years
This is the minimum round trip, assuming an immediate reply. It says nothing about whether anyone is there, listening, able to decode the signal, or willing to answer.
Flux
59.081×
relative to the same source at 10 pc; flux follows 1/d².
Earth–Sun separation
768,639.508 µas
one astronomical unit projected on the sky.
Ideal diffraction aperture
0.18 m
Rayleigh separation at 550 nm, before contrast, wavefront, crowding, and photon limits.
If someone is there, can we know?
A technosignature needs an evidence graph too
An anomaly begins a chain of natural-hypothesis tests; it does not end with an intelligence claim. Non-detections constrain only the frequencies, powers, directions, times, and signal classes actually searched.
| Channel | Evidence needed | Natural / instrumental alternatives |
|---|---|---|
| Narrow-band radio | frequency drift, repeatability, sky localisation | radio interference |
| Optical / near-IR pulse | time-coincident photons and repeat events | instrumental and atmospheric transients |
| Industrial atmosphere | retrieved abundance inconsistent with tested natural pathways | photochemistry and retrieval degeneracy |
| Artificial illumination | phase-locked night-side excess | thermal emission, clouds, albedo maps |
| Waste heat | spectral energy imbalance | dust and natural infrared excess |
| Transit anomaly | repeatable geometry inconsistent with tested bodies | rings, dust, activity, processing artifacts |
Staged research programme
FIND A WORLDDETERMINE WHAT IT ISTEST LIFE-COMPATIBLE CONDITIONSSEARCH BIOSIGNATURESSEARCH TECHNOSIGNATURESCALCULATE SIGNAL DELAYCALCULATE TRAVEL LIMITSCHOOSE THE NEXT TEST
The boundary is the product: what we know, what we can infer, what we could test, and what we can only imagine.